Keep your body language open and approachable by having good posture and looking relaxed. Avoid crossing your arms, covering your mouth, fidgeting, or looking down.
Ask plenty of questions. Most people love talking about themselves.
Have a sense of humor. Laughter is an excellent aphrodisiac – not to mention a great way to ease an awkward moment.
Don’t offer your number, give it. Always have a little piece of paper and a pen on your person so that you can scribble if down quickly and without much ado. The less of a big deal you make of it, the smoother the whole thing will feel.
Leave him wanting more. If the conversation is going great but will probably wind down soon, cut it short before it gets stale. Keep it simple: “I hate do to do this, but I’ve actually got to be somewhere. I’ve really enjoyed talking with you, though, so here’s my number. Let’s do this again soon!”
Smile and be friendly, but don’t come on too strong or you may seem desperate; show interest in the person you’re flirting with, but stay interested in other things that are happening around you, too.