Follow the words of Superbad. Women in bars = bad. Go to a park, an art gallery, a concert, etc. And I think 'hello' would work just fine, if you like, 'accidentally' bump into her ;D
Don't try and pick up women if you go to a dive bar. Also, this may be a little cliche, but be yourself. Say hello, try and start a conversation, see if you can buy her a drink but make sure to take the hint if she doesn't want to talk to you.