Greetings
I am a new player to Ars Magica. I really like what I've read so far. a lot of players up here rave about it.
I am, unfortunately on a limited budget, and while I'd love to buy all the books, but can't on my college student lifestyle.
What books, other than the main book are best to pick up ?
P.s. Has any one done any Ars Saga/campaigns in other "world" settings?
Welcome, sinb!
Lots of opinions on "best", and it all comes down to personal preference, and what you intend to do. Buying a book that centers on the Fae, or Demons, or France won't do you much good if your Saga (that you run, or that you are in) isn't going to revolve around those.
That said, tho' all the books seem well written for what they cover, but there are some that are of "general interest", that is, that lay down a groundwork that almost anything else can be built from. (And others will chime in here, I'm sure, if only to tell me I'm wrong!) 
"Covenants" expands on the rules in the book, and on labwork and texts, and so can be useful for any saga and most any mage. A Covenant is, to many, the most important character in the story. Magi come, magi go, but the Covenant continues...
The "Houses of Hermes" books (3 of them) are nifty, in that they expand on the houses, and give you a sense of the politics and differences between them. More Virtues and Flaws, more options - more is good. Choose the one(s) that cover the Houses you're interested in, can't go wrong.
"Mysteries" gives characters both an IC secret society to belong to, and IC goals to pursue beside inventing spells, and a way to add "virtues" after CharGen. (So, it can be either very rich, or very abused, depending on the StoryGuide.)
"Ancient Magic" - The premise of the Hermetic Order is that it organized many views of magic into one concept. This book suggests some of those other, older approaches, and how to integrate them into your saga/magi. Nice, some rich storylines. More "saga level" than individual mage, more of a StoryGuide book. (& see next comment below)
"Domains", Area Specific, "Cities", "Arts" - as I touched on above, these are indispensable IF that's what your mage/saga are all about.
(But the key is to get your buddies to pick up a book or two!)
And, yes, other "worlds" have been tried, and those folk may well speak up here. But one of the huge attractions to AM is the fact that it is NOT in a "fantasy world", but one where all the Players already have a feel for the same world, and more or less understand the society and the repercussions of actions. "Mythic Europe" is a common, familiar ground that no amount of Game Master description could rival.
But another huge attraction is the power of the system, and its adaptability - so, if you're excited about it, do it! Let us know how it goes!
HAHAHA ! like that'll ever happen ! my friends are even cheaper than me. Not poorer, just cheaper.
Also, I'm working on some campanions and grogs to get the feel for the basic character concept (:oops: still trying to figure out the magic 
).
But i was wondering, are their rules for Duel Wielding or Two Weapon Fighting ?
And, can a blind character, have "Secondary Sight" ability?
(We must have friends in common.)
There are many, many aspects and details of the rules that are not interpreted In Canon - and that's intentional. It's up to the Story Guide, or the Troupe, to decide on exact interpretations of those facets of the rules.
Combat has been down-played from 4th ed, emphasizing the mages over the "player character" type characters. Take a look at the given values for weapons, keep things in balance (ie, no "uber-combos"), and fake it. (ie, There's a reason people use shields!)
Since 2nd Sight is a "supernatural" ability, there is no reason to define it in narrow terms. Altho' the question is not addressed specifically, imo, if it makes a good story (and doesn't unbalance anything!), I'd say "great idea!" (And, in this case, I do - Great Idea! I might even steal it!)
Same with a LOT of virtues/flaws and other game elements - if they inspire something similar, and similarly balanced, then if it works for you, it works.
If Ars is anything, it's open ended, and invites creativity within some fairly flexible common bounds. Canon (ie, the rules as previously defined in hard terms) tries to create a boundary so the game isn't just "stuff!" happening, but beyond that, it's largely up to the table.
Off course the blind guy can have second sight - he can only just see the things second sight shows him and no one else. I actually made a character on a similar notion - making him blind but with visions and magic sensitivity, both tied to his eyes (the story was that the sparkling sights of his sensitivity had in the end blinded him for anything else, but that and his visions).
First of all, welcome! We all love Ars Magica and hope you will, too.
As to supplements, I think Covenants and The Mysteries: Revised Edition are a little too complex and detailed for newbies. I would steer you toward Houses of Hermes: True Lineages as your next step, because it gives a lot of flavor and definition to the Order of Hermes.
There aren't any in Fifth Edition. If it is really important to you, you'll have to make up your own rules. Though my impression is that in historical Europe of the High Middle Ages, fighting with two weapons was done rarely, if at all.
Sure, if you want. This is a good time to introduce a concept going way back to the early '90s on the Ars Magica e-mail list: "Do whatever works for your game" (known as Robbie's Mantra to us old-timers). 
In spite of the way the rules have grown to cover a lot of situations, the game in my opinion is still more story-driven than rules-driven. A lot of detail (like your Second Sight question) is left to your own sense of drama and/or common sense.
Some friends and I ran an experimental 'living' ArM saga back at the beginning of the century (now there's a phrase that's still odd to write) set in a world of our devising. TBH all we did was take the general medieval tropes and transplant them onto our own map.
Most of the Hermetic stuff remained unchanged although we had fewer Tribunals and Covenants. We had a powerful Dragon that had been accidentally summoned into the world by house Tremere which had eaten a whole Tribunal and set itself up as King. The Church were "The People of The Book" which were divided into three competing factions (akin to the Christians, Jews and Moors) and their major point of contention was, IIRC, whether everything worth writing had already been written, or if only new things were worth writing down, or something in between. Our Jerusalem analog was basically a glorified library and enough decent books gathered in the same place and cared for by a librarian could generate a Domnion aura.
There were also northern barbarians and a kingdom famed for its brassica. The experiment was successful; ArM4 gave itself over to a multi-SG near-Troupe living saga. However we couldn't sustain interest in the local player base and thus didn't repeat it.
I'll chime in here...
In order of importance...IMO
Covenants, City and Guild books- These expand on your game. The usage of these books is only for those that want to 'keep track of every last copper'.
If you have never run Ars Magica, I would suggest Guardians of the GForest. Why? because it gives you a whole tribunal description.
Even if you do not use it, you can see how a tribunal setting can look like. Politics, mundane stuff, faerie, divine and infernal interactions, the magic of the land, mystical places..... enemies, villains and heroes,...
Basically you get to know your enviroment. TYoyu can pretty much ignore everything in the supplements and run a 100% successful Ars magica saga. What you can't dois run a saga in a blank environment. So, anything that helps up in building the surrouinding is good.
My saga is set in britanny, and I have borrowed quite a few things from GOTF.
If you do not have time to think about everything there, you can set yourself in Triamore or use the saga of the rhine gorge to set the saga in motion.
And if you get any of the supplements beware the rules creep that there is all around the 5th edition books!!! You can ignore them and still use the books, but quite a few pages are destined to rules.
So plan B would get the Michelin guide to the area where you plan to play your game. Might be more useful.
Cheers,
Xavi
Here are my opinions;
You can run the game right out of the core rulebook for years without any supplements at all. I played from 1988 through 1994 using only the core rules (ok different, older, more buggy core rules with less helpful information provided). There's a great deal to be said for running the game in this fashion as well, you feel free to improvise and make stuff up because it is crystal clear that there is no "correct" answer. I was a college student with no income and "frugal' friends.
All of the fifth edition stuff is great in my opinion.
The books that I find myself referring to most often are:
Zero-ith:The book of mundane beasts: atlas-games.com/pdf_storage/ArM5Beasts.pdf because it's free, because in a perfect world it would have been in the core rulebook, and also because I took the effort to link to it.
First, Houses of Hermes True Lineages this is the book that tells you how the order works, if you want a game centered around magi politics this book is for you.
Second, Covenants: the list of boons and hooks are a delectable smorgesboard of great stories ready to be pulled from the players not just the storyguide and the lab personalization rules are a bit heavy but they make the character's labs incredibly cool. There's some other neat stuff in there with books libraries and finances but I'm less taken with it.
Third (tie), The other house books (societas and mystery cults) these are great for characters from the houses covered. Mystery cults might just be my favorite book ever for the line but it isn't the one that I turn to most frequently. the Mystery cults book is a bit more essential for character who are members of a mystery cult than the societas book is for characters from a Societas house. But the Societas covers normal hermetic magic in some depth in a way that the Mystery cults bok dosent
Fifth (I'm lying it's not really fifth for me, I've not used them yet) You also might want to get a setting book, Lion and the Lilly and Guardians of the Forrest are the two tribunal books that are written for fifth edition they're both great, Guardians has a setting of magical guilds trying to force their agendas through the tribunals and ancient enchanted forests with hidden magical powers being endangered. Lion and the Lilly has ancient battered covenants with occulted histories competing in magical tournaments for the meager resources of the area.
Sixth (tie) the realms of power books for the infernal and the divine, the nature of the other powers depicted in both prose and game mechanics.
ninth the rest: Mysteries revised, city and guild, ancient magic, the broken covenant.
This list is highly dependent on what you want to do. If I only could grab one supplement I'd probably grab ancient magic and spin a story about the rediscovery of Hyperborian magic, meanwhile Ancient Magic is tied for last on my list.
You don't need any of them. All of them are great. Get the one that you'll use the most. If demons are going to be your chief antagonists get the infernal book, if secretive subsects with mysterious powers are the subject of the day get mysteries revised.
Welcome aboard, I hope you and your friends enjoy the ride.
Now, everybody has an opinion as to the best books to buy and I'm no exception. But I'd take it from a different angle.
Where would you like to set your stories? At the moment, if you want a book to support your saga, you've got Germany or France (to put it simply). For my money, I think the Guardians (Germany) leans towards the political (with the Guilds etc) and Lion & Lily (France) certainly feels a little more "romantic". If I was starting out again, of the two I'd go for France.
What kind of stories do you want to run? The great thing about Ars is that the history is there to be used and abused to the degree you see fit. If you'd like a slightly heightened more fantastical and focussed on the magical I'd probably go for Ancient Magic and get your magi out there and exploring. If you'd like lots of sneaking around and having your players do lots of secret deals I'd go for Mysteries Revised. Both give your players tons to do but each has a distinct feel. If you want things to be a little more grounded, I'd plump for City & Guild. It's a nice book that really supports companion and grog characters (and I have a feeling it will synergise nicely with the towns and cities in Lion & Lily).
Who do you want as your big bad guys? One of the problems people I know have with the game is that it is sometimes hard to see just what overt threats there are to magi and their Order. You can play up on the Infernal with the Realms of Power books and they make good bad guys.
Although the Houses books are brilliant (I don't leave home without them) and I'm finding Covenants more and more useful, I'd advise you to push those down the priority list.
Use the core rules. Build your stories with those. They tell you all you need to know about auras and regios and spells and powerful magic items that magi would kill to own.
With the core rules you can easily tell stories of magi meeting kings and saving the lives of beggers. Your magi can hide themselves from society for years on end and then emerge with apprentices, familiars, and talismans. There's so much there to explore that sometimes the other books get in the way.
But there it is. If you wanted a few books to start with I'd go for the Core Rules, Lion & Lily, Realms of Power: Infernal, and Ancient Magic. You get the fantastic essential wizardly actions, a setting for your stories, hints on the darkest of enemies with which to confront your players, and you get temptations to take your players out questing looking for forgotten knowledge.
What more could you possibly want. I'm quite excited myself now. Where are you playing?
A very good book I find is The Infernal, and The Divine is very useful in a different way. I like the Infernal in particular because it inspires so many story seeds - but demons are not to everyones taste...
cj x
Yup, I find myself reading and re-reading the infernal most than any other book.
I must admit demons make great story seeds, especially when your players waste a season of lab work only to discover a slightly overactive pig in some distant farm.
The only downside is once you get a few encounters with demons, it doesnt take long before house guernicus come and camp in your covenant and start sniffin around your every activity.
Well. China...they sent emmisaries west looking for help against the Mongols.
The weirdest I did was a sort of Stargate/Julian May's Galactic Milleu Sequence thing, with aliens and so on. Mars has a lot of Ignem vis on it...not so much Terram. though. It started with a crack in sky, literally, with a piece of sky-blue glass five miles long an a mile high crashing into the ocean and the mages nearby going "Um, did anyone else just see a piece of vis the size of a small city land in the Atlantic?" That was cool, just for the shock value. Then people kept turning up through the hole in the sky.
Several of us have done American, Arabic or modern settings. My American setting was a sort of Spanish/Flambeau Carribean pirate thing where they arrive in South America just in time to meet the Blue Hummingbird people, who are what happen if you send Diedne (druid) magi off to a land that worships the sun by cutting out people's hearts. That was a lot of fun.
I know a few of us have done Roman settings. I've thought about and Egyptian one, but never run it.
I ran a game several years ago (11 years ago I guess) set in a fantasy world where the PC's were the only magi in existence. The former servant/apprentices of an "immortal" wizard who had just died. This NPC of a thousand flashback scenes had kept all of his knowledge to himself fostering groups of laboratory assistants and then slaying them when they became to powerful for hundreds of years. The PC's had to uncover their history while squabbling over the limited resources of their covenant.