I'd love to say its easy, but the truth of it is that its even worse being a drummer because you are the beat of the song, and if you mess up everyone will hear it, and it could possibly through the other instruments off. That being said, make sure you learn all the songs perfectly, then its just a case of saying I can play everything fine, just imagine it as another practice sessiosn. As much as it sounds easier to say than do, you cant be nervous, if your nervous, your tight and tense, which do not go well with rythmn. Just loosen up and be confident.