Hello!
Well, I don't know if you're a drinker, but a couple of cocktails can help you relax.
And keep in mind (this is what I've found) you don't really have to worry about whether you're 'doing it right' because he's going to think it's great no matter what. Just bend over and wiggle a lot *Schwing!*
But the more you do it, the more relaxed and playful you will get. The first time is just a little nerve wracking because you're wondering if you're going to make an idiot out of yourself...but now I really don't think that's possible. Like I said, he's going to like it no matter what.
I always start up close because it helps me get into it if I can touch him and kiss him and, uh, grind on him.
Good luck!
oh, and as far as what to wear? That is completely up to you. Personally, I don't like messing with alot of clothing, so I usually start in lingerie of some sort...sometimes a slip...and
always stockings and a garter belt.