Raz, you're a great performer of your work imo.

Definitely agree about choosing stuff to suit the audience.
My advice:
* Rehearse, rehearse, rehearse. Doing it in front of the mirror, or recording yourself and listening back can be helpful. Practise performing to a friend or two beforehand.
* Remember to breathe, and don't go too fast! Nerves make most people go faster. Focus on reading slowly.
* If using a microphone, make sure you speak into it. So many people don't speak close enough to the mic, so that the audience can barely hear them. If in doubt, say a few words beforehand and ask if people up the back can hear you. A few words beforehand to break the ice is generally a good idea anyway - but try not to ramble on too long!
* Don't eat a meal or drink caffeinated drinks immediately beforehand. There's nothing worse than trying to read while you're in the middle of digesting food! And if you're sensitive to caffeine like I am, chances are your performance anxiety will be exacerbated (trembling hands and voice, reading too quickly, etc). I generally don't drink alcohol beforehand either, although if it's a more relaxed / fun gig and I'm aiming to make the audience laugh, then I might have one or two before I go on stage.
* Don't overstay your welcome - check the time limit with whoever's running the show.
I've done heaps of public readings, and I've become much less nervous about it over the years. I used to be scared out of my wits, but these days I absolutely love it.