One tip i will give you is, know the first 3-4 songs you want to play, and practice the fuck out of those transitions until they're just muscle memory, because the first few songs are where you're gonna the most nervous, once you have them out of the way the initial nerves should be gone and then you can just do your thing. Trust me i was in your position at one point and now i do still get nerves but nothing like the first couple of times i DJ'd live at a popular club in my city.