One of my favorite pieces of 'equipment' is a good hat to keep the sun off, and a pair of sunglasses. (I like the Dakine Indo hat with the flap that covers your neck).
Do NOT let your students wear their expensive sunglasses during the lesson. I had a guy drop his fancy Oakleys or whatever, and he let go of the bar and completely turned around away from the kite to look for them. He even stopped the rest of his lesson to continue the search.
Good luck to ya man, teaching isn't for everyone and it's tough to give up your water time. You'll know soon enough if it's something you want to continue in the future.
On that note, after almost 10 years of teaching I have nearly had enough of it- anyone wanna buy a lesson operation in Florida?

www.kiteboardingtampbay.com