I'd recommend a lax Kaos (give them a couple ropes/teleports/jetpacks to start with). Kaos scheme is great because they can play around figuring out weapons without instant turn loss from damage or missing their single shot by a mile. that can be very frustrating to new players, especially in a larger group (minutes between turns), this gives them a chance to settle in.
Hysteria is in my opinion the best scheme to improve shots, but the fast reaction times make it a bad introduction for newcomers (short wait between turns is a positive, once they're familiar enough to try it).