Dchan. Watch other instructors. Watch what works... more importantly, watch what DOESN'T work. You can read all the PMTS, PSIA, Perfect Turn, Art of Carving, Encyclopedia of Skiing you want. The weight of a good ski instructor doesn't come from how much he/she knows. It comes from how much he/she can learn while being thrown to the wolves.
You'll see kids. You'll see Beginner adults. You'll see other instructors getting lessons you wish you had. You'll get hung on a lesson while your cohorts chew the two feet of fresh you got last night. Some days you do the chewing. Sometimes things fall right into place, sometimes they simply do not.
Attend training sessions... as many as you can. Never take the spoken or written word as LAW. Laugh hard at least twice daily. Challenge yourself to hang up what you thought you knew about skiing and try a new approach. Mentally and Physically. Take risks both in lessons and on your own. Innovate. Be cool. Be a hard-ass. Be soft-shell. Be silly.