Send a flirty text message before the date to let her know that you are excited about it. A text message is much less pressure than a phone call, and it can be the perfect way to set the mood for the date. Just by sending an inside joke text, or a simple "Can't wait till tonight," you show up to the date in a flirty mood, which can put the date on the right track.
Joke with him throughout the date. Humor is one of the easiest ways to flirt, and laughing with him can ease the mood. Let him catch you in an obvious lie, or ask him silly questions. Act surprised when he answers your silly questions. One dating website recommends that you ask a silly question about what his favorite ice cream is, and act heartbroken when he gives you the answer, noting that you would have married him had he said strawberry. These playful jokes keep the mood light and flirtatious.
Rely on some of your nonverbal communication skills to be flirty. Run your fingers through your hair. Lean forward on the table when she's talking to you to show that you're interested. Ignore the pretty waitress. You can flirt with your words, but if your body doesn't match those words, the flirting comes off as fake.
Try flirtatious contact with him. When he makes a joke, give him a gentle shove. Give his arm a squeeze when he says something that you like. Let your fingers brush his when you're walking, but don't let him hold your hand. These small things heighten the anticipation of the date. They are the precursor to even better things on the date.
Keep eye contact. If your date brings you to a party, go and mingle on your own. but let her catch you looking at her. When she does, give her a smile meant only for her, and perhaps a gesture or facial expression that is an inside joke between you. Even when you're with other people, or across the room, you can flirt by keeping the night all about you as a couple.