Flirting is not about talking to a person while using smooth words to try to seduce them. That's for movies. Flirting is about talking to somebody exactly like a person your friend is trying to introduce you to. It's just regular conversation. If the candle never lights, then your chemistry doesn't match and that's okay. Life is about finding out what clicks with you and making the most of it. Relationships happen when those regular conversations start becoming mutual genuine interest in the other person.
All of these thing are a toss of the coin to be honest. If you know this person then you should have an idea how you will be received before you approach. If in doubt about this wait and be patient. When you find out more then you will know what is the best to do