By yourself, just sack up. Go in knowing that you have the skills, the more confidence, the more commitment, the greater success, if you go in thinking you will fall, you probably will. I've done it enough.
With friends better than you, follow and try to copy them, ask for advice, and play skate as it forces you to try new things and you might surprise yourself.
With friends worse than you I still like to play skate, I want to win so I still try things that I can't 100% do, yes I mess up but it makes for a better game. Or asking them about doing tricks, usually they have a better grasp on what you can do than you do at that given time.
Those usually help me, that and knowing that I am having fun, it doesn't matter what others think, I try dumb stuff all the time that probably looks lame as shit, so what?