Start renting out romantic movies and learn the lines that helps you pick up the ladies.
Ok, I have to say, first of all, as a girl (who also dates girls), this is not really the best way to go about this. We're not looking for lines. If you really want a relationship, learn about her first, be honest, ask questions and actually listen and share about yourself, too. Also, be direct and be confident. If you like a girl, tell her. Not only do most girls sit around for hours trying to figure out how a guy feels about them (you might think you're being very obvious, but we generally have no clue), but even if she doesn't feel the same way, it's nice to know someone likes you that way, so be happy that you made her feel good.
If you want a relationship, STAY AWAY FROM THE BARS. If you just wanna get laid, then go to the bars.
This, however, totally true.
I have yet to hear of anything that started in a bar working out well. Your best bet is probably to either meet somewhere that you both go because of shared interests, or through friends.
Anyways, good luck!