like he said, if you are wanting girls to approach you, they will be more likely to do so, when you are NOT with a group of friends.
I think it would be more of an advantage, as long as you don't look/act like a columbine kid. It makes you look more mysterious, more interested. And in my experience, if you are a loner, you are a loner because you want to be.
(again from my own experiences) Think of this...Society today is not very social, and you get used to the fact of "I don't know them so why talk to them". Pretty soon you'll learn that you are alot happier, alot more confident when you get to know people.