I Am Confused About Men

Like when I try to make contact by smiling or looking at them or glance back at them a few times, they seem upset and uninterested and irritated that I'm even flirting a little bit w/ them. BUT when I try to look nautalant and act like I don't notice them looking at me when they walk by or while I'm sitting in a food place, they get upset AGAIN, or maybe they think I'm not interested in them? But, I thought being interested in them turned them away like if I show interest back w/ a nice smile. -sigh- ugh, I don't understand men. What is wrong?????????