Singing
1. have plenty of water handy: duh. always helps to have a clear throat, and water does the trick. don't overdo it now.
2. sing with passion: no one wants to hear someone sing in a slow, monotonous tone. what good would that be? and, even if youre changing notes, etc., you've got to feel it and believe in it, or it's gonna SUCK.
Songwriting
1. write what you feel: don't write a song that has a topic you know nothing about or don't care about. it does'nt make for a good song. trust me on this one.
2. write with a passion: again, you can't do anything with out believing in it. a song you believe in will work, but a song that you sing with a passion, no matter the kind of song or quality, it will sound GOOD.
Performing
1. don't get rushed: this is a big mistake alot of people make. even the beatles made this mistake once or twice. it's easy to get so nervous you just rush straight through it really, really fast. slow yourself down. it's happened to me, i know.
2. loosen up: live, you want to be fun to watch. don't expect people to come to see you just because you're a rock band. you'll get a VERY small audience. it helps to be unpredictable.