DJ vintage said it. The biggest thing to remember us HAVE FUN. If your not having fun the crowed wont have fun. Relax and just enjoy the chance to share your passion with others. If your a bundle of nerves then it will make the crowed nervous.
The moment you drop your first track, take a second to breath and get into that beat. Start bobbing your head or tapping your foot or what ever you normally do when you play a song you enjoy. Allow your self to zone out to the music. Again the more you enjoy it the more the crowed will.
Good luck and let us know how it goes.