When I perform in front of other magicians at my magic meeting, I get nervous then I mess up. Can some one give me some advise?

Don't do it! Seriously, why put yourself through the torment? Perform for those you feel comfortable performing for.

My advise would be to make use of their knowledge as magicians. For example, we all know what a tt looks like, make a show of attempting to 'hide' it from view whilst in the act of vanishing a coin. They will assume you intend to use the tt. Don't. Their attention should be so fixated on the tt that your alternate vanish will go unnoticed. When they smugly accuse you of hiding the coin in the tt, merely smile and show it to be empty.

I'm of mixed minds about performing for other magicians, and which path I take depends upon my mood, the season, and what I had for lunch.

The first thing I do is my regular stuff because most magicians I know (myself included) don't care if they know how something is done as long as the presentation is entertaining. But when the mood strikes me, I do have a handful of things I do just for magicians, and it's not entirely unlike what Ben suggests. I do things that will fool magicians but most lay people would consider absolute garbage, because magicians have a peculiar way of thinking.

I pretend they are laymen and just do my thing.