OP, I actually have been doing stand-up in the California Bay Area since September, I just got back from an open mic tonight. The only advice I can give that I wish someone told me is, even if you're just doing 5 minutes, take your time. A lot of people their first time at an open mic think they're pressed for time and speak too quickly. If you speak too fast (whether you're nervous or whatever), it hurts the delivery a lot.
Also, I wish it was easy to say "be confident" but try to stay away from self-deprecation if you can. I've seen a comics tell unoriginal stuff, but their confidence and delivery won over the audience, so don't try to win their approval, have confidence that your stuff's funny and just do it.
Here's a
clip of my first stand-up in the US last september (spoke too fast, was nervous), and here's some of the stuff I've done
now if you're interested.
Good luck!