Hmm. Thorough planning, make all objectives as obvious as a coal pile in a ballroom, make sure that "is this for a grade" is a question always answered yes. Honestly, I am not sure I should even offer you advice- you taught a good many years longer than I have. About the only thing I can think of is, they may look like adults but they are not. Don't expect them to react the same as adults. And be prepared to hear some very adultlike problems- some things teens get into are positively awful. If I can think of anything that might help, I'd post it. But I'd say you know most of what makes a successful teacher at any grade level.