I have to admit, self-esteem is über important! I would recommend reading Joseph Matthews '
The Art of Approaching' to help with that; it helped me a ton!
But as one my friend (who's a 'natural') says: "
You gotta have da attitude!"
I'm still not entirely sure what kind of mentality I'm supposed to adopt in order to convey the right attitude, but I've found that if you just treat girls like your little sister, things go much smoother! I guess it has something to do with the fact that most guys would be happy to bring a crow-bar to the legs of any man who dares to hurt his little sis!
(Or am I just twisted like that?

)
One trick that I really like to use in order to get girls to 'despise' me is to pat them on the head; they "hate" this, and love me for it!
One girl might think that you're teasing her about her height while another might pull a feminist card on you; either way you're teasing them and allowing yourself a chance to study their insecurities.
Then, of course, you have to get them to fight for their value level; it's all about DH!
In any case, I have a similar problem as your own; it doesn't take long for me to become Mr.Good-Friend, so I have very few tips to say on that subject.

Lately I've just been trying to keep the friendly attitude at bay..
I guess the main thing is to keep reminding them where they belong: under your wing!