Being the flirtatious sort I never had much of a problem. Just be confident, be yourself and being humorous never hurts. I once jokingly told a girl that I was gonna marry her and she was going to have my babies after just meeting her. It works with my personality, I wouldnt recommend you say that though, granted I did end up marrying her and she has had two of my children thus far. I am pyschic I suppose.