When you're out together, try to sit near her. Notice if she moves closer or farther away. When you're sitting on a couch and your thighs touch, what does she do? Does she let it stay or inch away?
Look her in the eye when you are talking. Hold the stare for a little longer than you would a normal conversation.
It may sound corny, but open a door for her to walk through.
If you're sitting across from each other, gently put your hand on hers. Don't move it away unless she does.
Tell her she looks nice tonight. Compliment her hair or outfit.
Find out what makes her laugh. There's nothing like humor to cut the tension and loosen you both up.
Offer to get her a drink if you're at a party or bar together.
Touch her hand or shoulder when you hand her a drink.
Tell her you've been thinking about her.
Call her just to say hi and see what's she's been doing.
Send her a little note that says you enjoyed spending time together. An email is okay, hand written and dropped at her door or mailed is better.
Be careful not to over do it. You don't want to seem like a stalker. Look for signs that your flirtation is unwanted. Does she get off the phone quickly when you call? Do you send her long flowery e-mails, only to get one line answers in return? If so, back off and let her come to you.