Get him started putting together his "songbook" and, tune by tune, working out arrangements--help him to work out intros, the basic chord back up, substitutions, figured bass lines, turn-a-rounds, and solos--teach him where the improvisation goes, and where it doesn't go--that ought to keep you busy for a couple weeks, anyway;-)--also, play along with him, and teach him to play along with you--way to many teachers only use the guitar to walk through things when they work with students--oh, and do a little research so you can keep ahead of him--