There are some general points to consider.

First point, I heard before through an international professional psychology professor that, if someone is going to kill you, harm you by anyway, and you succeeded to make him/her laugh he will not continue his attempt. This is a psychological certainty.
same goes in dating, even if this girl considered you creepy and stalker person from the first moment and you succeeded in making her laugh, most probably she will be attracted to you and your mission will be somehow easier.

Second point, your chance in dating a girl you don't know on a social network like Facebook substantially increases by one of two points, your look and your popularity, even popularity has more impact than your look, for instance if you tried to date a girl on Facebook and she opened your profile picture and found hundreds of likes and comments, I believe that everything will be going on well.
yes this is shallow and superficial but she doesn't know you, so she should have to find something to be attracted to you, otherwise she will not react.

do you agree?