Welcome to the Sixth World is designed specifically for newbies. The opposition is fairly weak and players get a sense of how the mechanics of the game works. For a group entirely made of new players, I'd avoid CMPs for a bit and just start out with the Season 5 Missions, so after Welcome to the Sixth World, run through Chasin' the Wind. It's a notch or two harder than Welcome, but it gives the players a good lay of the land. Skip the optional encounters.