Think about it from a perspective of an average SINGLE girl if you can, not just your own personality. Also try to look at it in different situations. Example, next time I go visit my friend at her college, she has a friend that I want to know better but if there isn't good conversing time then I want to at least get her attention through eye/smile-flirting.
If said single girl is interested in you and you make eye contact and smile then it won't be as creepy as it is exiting. Just make sure you don't just randomly stare at her and star away, smile look happy and make it obvious that you're interested.
agreed with missatron. If you do it once and she likes you, then she'll probably keep looking at you too. If you do it once and she doesn't like you, it might be cute and flattering but if you keep doing it and she doesn't like you, you start to become creepy.
depends on how you do it, usually I find it flattering, it tames my insecurities and makes me feel pretty, but just don't say anything macho or sexual then its creepy.
if you admire from a far its romantic and cute. Being genuine is key!