How to help a socially awkward person?

I have a friend who is heading out into the dating scene for the first time in over 20 years. He has had tons of dates through online dating sites, but no one has wanted to see him a second time. He is a great guy, but really has no idea how to interact with women. He seems to have a knack for saying the exact wrong thing and coming off as creepy rather than charming. I have tried to tell him this gently, but he isn’t hearing me. Any advice I might be able to give this guy to help him over the hurdle to that second date?