Bottom line: If you are interested in sharing a man's company in a romantic or sexual manner ... tell him. Confidently and directly. On the other hand, if you are not interested in sharing his company in a romantic or sexual manner ... be bold enough to convey that to him as well.
Anytime your behavior toward men falls in-between those two points - what I like to refer to as "The Vague and Ambiguous Zone" - you are asking for unnecessary drama, resentment, and animosity from men.
Great relationships are all about excellent interpersonal communication skills. Start off on the right track with men of interest.