You don't need to stop being a perv, you need to stop being guilty about it.
Everyone looks at girls butts. The correct answer to "were you just looking at my butt?" is "yeah, so?" (Girls that make a big deal out of stuff like this are b'itches and should be ignored, as a rule.)
If you're guilty about doing "pervy" things, girls will pick up on this and be wierded out. If you're cool and act like it's your right, they should be cool too.
Being SEXUAL is good, read Pook's posts. There's a difference between being sexual and DESPERATE, though. Chicks are wierded out by DESPERATE NEEDY guys, but they LOVE guys who are sexual. The basic difference is that the sexual guy wants it, but he doesn't NEED it. He's not going to do anything he doesn't want to in order to get it.
In fact, better said, he's not thinking about getting sex; he's JUST thinking about how cute this girl's arse is (etc). Being in the moment as opposed to "trying" for anything.
Read:
Kill that desperation!
Embrace your sexuality!
Both by Pook. Think hard about how these two work together.