Answer:
^^;
I usually just try to become their friend-sorta.
I will usually try to get to know a guy, when I have a crush.
It is not to hard to figure out what a guy prefers- someone tough, some cute, ect.
So, once I know that(let's say the guy likes someone sweet and cute. I act a little cuter. xP) I just up the whatever factor. I don't change my whole personalty though.
-Shrugs-
Just my dorky way.