I have done tons of open mic nights in Isla Vista, santa barbara, california when I was going to ucsb and working on my indie singersongwriter emo stuff; so I have seen the feminines and the goofy and the coverband and the amazing singersongwriter play before and after me...
make sure you have whitty stuff to say before during and after you play
try to be less pitchy by sticking with one note and hitting it dead on, and more upbeat with the memorable choruses. good stuff, cheers d00d!