Well said, MM.
Hokay... (thinks back, back, to first AM campaign...)
AM is ~very~ diff from standard RPG's, tho' some others are starting to follow the trend. But if they're used to playing the predictable ones, this will be a big brain-cramp as many assumptions are challenged and broken. Accept that, warn them about it, try to get them in to a "new paradigm" mind set even before you crack a book.
First, I assume you know your players - as MM said, tune your game intro, and the start of your campaign, to them.
The biggest selling point is the magic system, and the flexibility of what is a "wizard". Unlike most other systems, no two will look alike, and often no two will have any spell in common. There is no single "best" spell, nor "most powerful" build - the varieties are endless. And with Spontaneous spells, all those annoying "cantrips" in some other games are not necessary - they're all at the fingertips of any mage who knows those Arts.
Another is the "Covenant" concept. A stronghold/safehouse from word one, complete with redshirts to show how the monster works, if necessary. Add to that The Order, and the challenge of "no fireballing the natives", and you have a different world-view welcomed by many players who are jaded by the hack-and-slash routine. (And those who aren't can be Flambeaux...) 
With regard to Troupe vs 1-character style, ~IF~ you think they can make the shift to Troupe style immediately, then go with it! If not, then... I'd suggest you start with just magi, maybe even still in gauntlet*. (It's not bad to only bring in Companions as they are needed - if a player wants to run a woodsy-ranger, but the Saga goes to the city... yeah. So, see where the saga goes, see what the Covenant needs, and if/when/as Players want to volunteer for a Companion role, have them fill it in as needed, rather than shoe-horn a private pet into the Saga. Be generous with re-writing existing NPC "specialist" characters (or even grogs!) to suit players who want to make them into Companions.)
(* If you start them maybe 1 year pre-gauntlet, you can introduce them to each other as apprentices, and have them think about their relationship to their Parens, and to each other as a means to mutual power, that can be a great lead-in to the later Saga. Or, walk them all thru their first year post-gauntlet - 4 seasons: 1 in study (fills in some gaps), 1 in the library learning a canon spell (diff from CharGen!), 1 in the lab inventing/designing a spell from scratch (a ~key~ player skill!), and the last inventing/designing an item - slightly different, but again, important. I found that doing this introduces the players to these activities that will be repeated so often later, and creates ~slightly~ stronger and better rounded beginning characters.)
That might also be a more "familiar" starting point - several characters working together, and also demonstrates why the "Troupe" system is desirable. If a mage is in the library/lab, they are hesitant to go respond to a mystery. Companions rarely are. Few magi will be combat thugs - handy to hire some. Emphasize that Companions are companions to the Covenant, not the same player's character - they should compliment the other magi, not the same Player's, for maximum play potential.
And that is what is diff from most other games - these are not "henchmen" who are just extensions of a single character, but independent additions to the story as a whole.)
Emphasize several points -
- That the Saga (aka The Covenant) is the key character. Companions will die, magi may die, but the Covenant will continue, and that will be the continuity.
As more than most any other game, The Story is what is important here, not the individual Character. Make sure they understand that. A good death can add more to the story than a dull existence in the lab.
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Resources. As mentioned above, downplay it. In my first campaign, I had one player go a little crazy in the head, and took every "money making" spell in the book - not only could he not use them all without getting into trouble, he found he rarely needed even one. This game has a different premise than others, where simple day-to-day survival is not a guaranteed, and having a wealthy stronghold and guaranteed income is only for high-level characters.
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CharGen - urgh. Don't underestimate the time needed. Possibly take each player aside individually, before the "first" game session. Players tend to go shopping, down the list of Virtues and Spells, and that is (arguably) the worst approach, and completely non-productive. I'd ~strongly~ suggest that you explain the basics of Magic - the 5 Tech's and 10 Forms, and then, even before they read the rules themselves, you tell them to pick a "concept" for their mage, and have them stick to that concept - at least for their first effort.
(I'm embarrassed to bring it up twice in as many months, but here:
A "How to" of Magi CharGen for the Boggled )
The same that is true for setting is true for theme and central interest - find one that everyone can get on board with. The sooner you can give the players a feel for the "theme" of the campaign, the better. Having one mage who chases the Fae, one who chases the Demonic, and one who is only at home in the Lab or a Library can be a formula for at least one always being a fish out of water, and one player bored*. If you see that one interest is high on everyone's list, then mention that - and don't let one player expect to go in a contradictory direction.
(* Before anyone says it, stop. Yes, it's ~possible~ to twist any plot to include any combination of elements - but the fewer ~necessary~ to include, the more creativity and time that can be spent on the common interest/focus.)
Avoid letting new players create magi who can barely cast their massive combat spells - a sure way to die fast.
Or even use pre-Gen for the first session. Give them a flavour of what's possible, and how it works. (Or allow them to toss away their first efforts - those can become NPC's at a neighboring Spring Covenant.)
In short, don't expect to dive in on the first session, nor expect Players to start to internalize the game before the third or so. Don't start with an "adventure" that will take many sessions - short and tight, even if several are tied together by some greater elements. Give as much world info as you can, and some meta-info about where this "group" wants to go with the story. Use their ideas as well as your own. Be generous with mundane elements - grogs, the Covenant. Focus on the magic, the magi, the Covenant, the Saga.