I am a novice GM trying to run Ars Magica for a few friends. I found AM by accident while looking up information on another role playing game and immediately fell in love with the system, however I am the only one in my group who knows anything about it. Because of this I am the one who has ended up agreeing to run a campaign/saga of Ars Magica for a small 3-4 person group of players. I have some experience in GMing, specifically with Symbaroum and a couple of D&D sessions, and am aware of the vast differences between these systems and AM. I know it is a complex game but I really do want to learn these complexities. I am here posting this asking for tips and tricks for a GM new to this system. Thank you for any help you provide.
That's a very broad question, making it hard to answer 
Since magi can be quite complicated, you might want to have people write up a grog first, then run a short introductory story with those, to get the basics of the system introduced - then make magi characters afterwards.
We've also had great fun playing apprentices, which introduces the magic system slowly as well, since young apprentices can do almost nothing anyway
Running an Ars Magica game is an adventure in itself. If your players are not sure about what kind of magi they would like to play, it might help to use the templates from the core rules for a couple one-off sessions to get used to the system before spending time figuring out what you want. A good story to start with could include a scene with mundane interaction, a scene with combat, and a scene with some sort of problem-solving. This would give everyone a little taste of the various mechanics around ability checks, combat, and spell-casting.
When my sons wanted to learn to play and how to run a game a few years ago, I wrote up one of the adventures I made for them, along with suggested spells that might be helpful in each scene. I posted it to my blog this morning, if anyone wants to take a look: https://rpgwandering.wordpress.com/2019/01/18/a-first-ars-magica-adventure/
Welcome to the game!
Keep it as simple as possible to begin with. Don't try to necessarily grasp everything, because ArM is vast.
Maybe have them be young magi in an established covenant, where the older magi send the youngsters to deal with all problems, because they are too busy themselves. And let the problems be fairly low key, perhaps do one faerie story, one with a magical beast, one with a nobleman, one with the church, one with a demon - so they get a feel for things.
Character creation can be difficult, so - as someone else suggested earlier - give them each a template magus. Otherwise, let them explain what they'd like to do, and help them design the magi - if you know the system well enough that is.
Another approach for novices is something I had a Sg do many years ago. I was experienced, and still enjoyed it, but it was good for the less experienced players in the group:
Let them design 10 year old children, with up to 3 points of Virtues balanced by flaws. GIve them each a short story about how they were special (or weird) and brought away from society by different magi, and all taken to the same covenant. Let the magi teach the children about the Order of Hermes, supernatural things, as well as the grand concepts of magi. But keep it a secret which magus is from which house. Run a low-key story at the covenant, so they get a feel for using abilities, how personality traits work, and what a covenant is like. Then have the magi test the children, with a few mini stories for each player alone, and have the player make some choices foe the character. After this, each of them is taken as apprentice by a magus, and the real teaching begins. Let the choices they make affect what House their parens is from; eg. a martial approach means Flambeau, a studious child is Bonisagus, a scheming on is Tytalus etc.
The suggestion I give pretty much anyone asking for advice is "Don't be afraid to be wrong." Rules are hard to remember, and if you make a mistake, go with it. Tell your players that a mistake was made (Ooops, spontaneous penetration is halved too!) and move on, pretending that they got lucky (or unlucky). using the starting templates for magi is a good idea, but let them choose different story flaws if they want. I like grog-adventures (more than anyone else in my group), and always like getting players to build a personal grog (ideally for a different character's magi). If you aren't using the giant mess of rules from the Covenants book, I suggest sticking them as a chapterhouse or faction of a much larger covenant so you can easily adjust their library access up (or down if you gave them too much early) and their vis sources, and so on. have them design the personality and abilities of whoever their 'patron' in the primary covenant is, and then you can start having things go wrong!
Another neat trick to deal with mistakes and retcon: the story you are playing is not what actually happened, but how it is remembered 100 years later.
So I was in the "Revaluing the text economy" thread and thought of you. To make things simple you could very easily make your library be very consistent. Summa on every art L15Q10 and every magus relevant skill L5Q10. Just to pull numbers out of the air.