So I ran a game at Garycon with all new players. I'd spent about an hour beforehand, discussing some elements of the setting-- mainly the Order of Hermes and a bit about the realms.
We had one ringer in the group-- which helps, although I could have filled in this role, if necessary-- and he played one of the two magi. The other was a complete newcomer.
I reinforced, several times, that all roles are just d10 + Characteristic + Ability (+ Sometimes modifiers), and we stuck with that for nearly everything. By about halfway through, they were cruising on that. We had one exploding roll actually hit 41, the second highest I've ever seen, and from a grog again, too. We had two botches, which were fun to play out.
The table had two magi, three companions, and two players running grog turb sergeants/a captain. They saw how all the components could interact, how we could cover extended periods (the adventure took place over a few days followed by a few weeks travel), and how not every encounter needs to be resolved by punching in the face; I even had the grog turb captain itching for violence.
They did a great job playing with the magic-- although some of the magi's sheet is currently in a form of "Do you want to cast spontaneous spells that involve X or Y?" which I may revise to include actual stats, so a ringer can easily work with it.
All of the players ended as fans, and said they'd definitely play again. One player was going to pick up a few books to try at home.
I also played in a game at Gencon, where we were all magi. We had four out of six players who were veterans at that game, but the new players came online pretty quick. Hopefully, we'll get that adventure in Sub Rosa #21. We had some grogs along, but they were mostly handwaved by the GM, IIRC.
I think having all of the roles evident at the table is a good plan, and a story that involves all of the roles. We were playing Timothy's Escape to the Tin Islands, which I've run many times for tables of mostly-new players (usually no more than one veteran player) and done some edits to for how I play it. So far, most tables approach the different parts of the first act differently. I've only had one group get to the Tin Islands, and they only got a session into that act. We had to quit with the first appearance of the main antagonist.
I use English verbs and nouns for the Techniques & Forms, and try to repeat back the Latin to get people accustomed to using them. I've got my 12-year old on board with the magic system after about a half hour of review, so most players should be able to handle it. The scenario definitely helps. I think having one which actively involves all the roles and has a certain level of tension and urgency helps. I think involving the whole covenant, including the covenfolk helps to show the community element of the game. I think starting them in a familiar, urban environment helps, then transitioning to a bit more fantastic environment helps.
-Ben.