Congrats on the job! That's awesome.
My only advice is hit 'em hard and fast. I always play the strict teacher right away (are you coming in the middle of the school year or the beginning of the new one?), so they know my expectations are high and then soften up after that. But, a little fear is good for them.
Oh, and don't let them see you shake. Even when I have no idea what I'm doing (which is rarer these days), I've always found that pretending like I know what I'm doing is the best way to do things.
You're going to be amazing!