Your best bet is to get to know the girl first, and let the feelings naturally come up. That is, if you are willing to wait and want the girl to genuinely feel attraction towards you.
Contrary to popular belief, women actually want a real man with character. Just think about it, if you were in her shoes, you wouldn't want to date a sleazebag either, but you WOULD feel attracted to someone who you can TRUST, and is KIND and RESPECTFUL to you.
UPDATE: It IS creepy to ask a girl out that you do not know, and creeping a girl will turn her off AS SOON AS IT HAPPENS. When talking with one, get to be her friend first so that there is rapport and she feels comfortable showing interest in you, which will help A LOT in growing her attraction for you. MOST OF ALL, BE GENUINE!
WOMEN DO NOT WANT SEX, THEY WANT RELATIONSHIPS AND EMOTIONAL CONNECTIONS
NO WOMEN WILL HAVE SEX WITH YOU, AND N.E.V.E.R E.V.E.R MENTION IT, AS IT WILL JUST CREEP HER OUT EVEN MORE! (This is a response to the other comment)