How to turn someone down?

Look him straight in the eye and softly, without getting aggressive, tell him, "Listen, I think you're a nice enough guy; but I'm not attracted to you in a ual way. Secondly, I just got out of a long-term relationship, so I'm not ready for another. Let's keep things light and we'll get along. Otherwise, I'll have to remove you from my circle of friends. Okay?" And wait for an answer...