Make sure the person you are about to flirt with is a potential mate and worth your time. The object is to get involved with the person, not make them think you are interested and then ditch them.
Give out your phone number, but only after being asked two or three times. Reply with an "I don’t know" or "How do I know you’ll even call?" When the person calls, decide when you want to answer and when you want to return their call.
Act disinterested, even if you are writhing with anticipation on the inside. You want to come off as a challenge, not an easy target.
Leave a little bit of time between conversations or meetings.
Call them when you know they won’t be at home. Leave a message stating that you are disappointed you missed them. This will show you are interested, but still make them long to speak with you.
Deliberately hold the person at bay. Do not come off as too willing or too needy, this will completely shatter your image of trying to be more alluring.
Keep a little window of hope for the person you are trying to play hard to get with. Do not take this game too far. You need to remember to keep the perfect balance of hot and cold. Otherwise, your target may consider you impossible and give up.