[Aur0r4]

One big one is gaining and maintaining the student's respect. This is a mixture of enforcing rules/behavior policies but also building rapport. Too much enforcing leads to students who behave in front of you but develop a common connection of not really liking you. Very unlikely to behave when you aren't around. Obviously being too soft and "fun" causes them to disobey rules right in front of you.

Don't be afraid to joke around with students.

The other big thing is letting them know that if they DO break something that they should feel comfortable telling you so the problem can be fixed. This goes back to my initial comment. If they are terrified of breaking something, they will only hide it when they do. We have all broken lots of things....usually professionals have epic stories of screwing up.

As long as something really, really dumb didn't cause it, I don't get worked up. They don't need a long lecture to know not to do that thing again. Especially if they have your respect, they'll feel the worst about letting you down.

And, then again, I've done plenty of really, really dumb things myself in my day...