Handshakes are very important. Usually, this is your first opportunity at "keno" (establishing physical contact.) Our hands are filled with tactile nerves. If your handshake is loose and feels clammy, you're signaling that you are anxious, and this will naturally elevate HER stress levels.
Give her hand a firm, but not bone-crushing, grasp. Pay attention to her grip also.
I've found that women who give firmer handshakes tend to be more adventurous. This must come from the fact that they're more comfortable socially, and confident in themselves.
As the conversation develops, use body contact to build the sense of connection and generate sparks. Subtly touch her knee as you tell a story. Put your hand on hers for a brief moment, as you both laugh at a joke.
(Her inner forearm is a GREAT spot to use a flirting touch, since this zone of her body is rich with nerves.) But don't look at your hand as you touch her. Just do it, as if it's a completely natural gesture.
Women are attracted to deeper-voiced men. This suggests high testosterone levels, which is a sign of strength and reproductive ability. If you don't have a naturally deep voice, lower your tone slightly when you engage her in conversation.
Speaking slower also helps when you are flirting with a girl. A deep voice, combined with eye contact, can have a hypnotic (and deeply attractive) effect.
Also, talk at the same pace she does. This enhances the sense that the two of your are connecting and bonding.
Watch an insecure guy flirt with girls, and he'll almost always speak at a faster clip than she does. (This is very true with "funny guys," who try to use constant jokes as substitute for real conversation.)
Mirror her body language. Couples who are attracted to each other tend to subconsciously "mirror" each other. By mirroring her, you are again building the sense that you are connecting on a deeper level.
DON'T fidget. This sends the message that you are nervous, and will trigger the release of stress chemicals in her brain. When you are calm and relaxed, you encourage her to go with your flow. You don't need to use a lot of flirting body language. Just be relaxed and comfortable, and smile and maintain eye contact.