Don't be anyone you wouldn't be if she were anyone else.
"Be yourself" is crap - nobody is themselves on a first date.
Here's the best advice I can give you - Be a neanderthal. Be a man. Stop being a *ussy.
When you're out on a date with a woman, any woman and a decision making moment comes up think to yourself "Self, What would a MAN do here?" Then do that - unless your outlook on life is sensitive and whipped - in that case don't get the zima - do the opposite of that.
My wife is a little higher power than me and very independant. I treat her like a woman and I behave like a man with her. It's true, sometimes she laughs at me (maybe more than sometimes) but at least I'm honest. Be a gentleman, but most importantly in all aspects of life be two things, be respectible and be a man.