Your problem is certainly not an uncommon one with many guys finding it hard to get a foot in the door and then not knowing what to do or say to get that door wide open.
I think most men need to consider that women can sense desperation, and that you're not too comfortable with female company. Some men are born charmers but sadly many really need to make an effort to shine. You may need to try just being yourself instead of being conscious of trying to impress. Show that you're on here to have some fun and laughs. Don't seem too keen to hook up. It will make them feel more relaxed about talking with you instead putting their guard up.
As for your profile, I can certainly start with your username. I'm sure you're not a pr&*k but you don't need to advertise it! Crass usernames really put women off so consider a name that is friendly and confident. Perhaps something that tells women what you're into (eg - SkyDiver72). Good luck!