Yeah tip us instructors
What bugs me is our staff in other departments get free lessons from us, they can just turn up and join a group if there is a spare space. Now they of course act all pissy if we are in the bar and don't tip them, however they turn up to a free lesson, take up our time that could be spent on paying customers and then just stroll off at the end. So those people didn't get a tip for the rest of the year. I don't mind not getting a tip, but when they demand one then they should be doing the same.
/rant!
Anyway generally anyone who gives you a bill to pay would be after a tip, taxi drivers also. Bar staff. You'll soon figure out who does and doesn't need a tip.