Over on my role in church, is an alter server. I'm pretty sure you know what that is. Whenever I tend to get nervous, I think over to happy things; or pull my mind away from the fact that i'm standing in front of a hundred people. As of now, every time I have to do something public, I tell myself: There's nothing to be ashamed of. There's nothing that people will make fun of. You won't mess up.
It's just a little thing I do that helps me.
Be careful when you're up there though, you might feel a little jittery(nervous). I think it's adrenaline, but try to not let it get to you. I hope you do great this Sunday!