How to talk to a girl-1

do and don't
 
It's all about confidence! Maintain the attitude that she is lucky that you like her (make sure you are smiling, and in a nice way)--and if she doesn't see that she is lucky--well, there are plenty of girls who will. If you are not that confident, or you are shy, you should work on this dilemma by trying the ideas with some girls who are not your special crush. Learn the process with some nice girls who are friendly, and are not too scary.

Work up to that special one when you have had some good results with this process (and feel like it). Having butterflies in your tummy and a catch or shake in your voice is fine; just don't give up or fall back just because it makes you feel shaky: that is actually a sign that she is impressive to you--tell her that she impresses you if you want to. Be prepared to tell "what and why" you notice her (to show that you mean it)...

Compliment her: Tell her she has a beautiful smile or beautiful eyes, but do not say something that is not true. And--don't say them one after the other! (It is highly recommended that you must talk about other things before complimenting or else it feels awkward)

Girls like it when boys try to defend them when someone makes fun of them or threatens them. However, in other settings like a workplace or college, these things would rarely occur.
In most cases, if you pick on her and pretend you hate her, then she will never like you. She'll think that you do not like her, so she won't like you