Just added this girl on FB. Saw that she was friends with my cousin, so I took the advice of someone on this forum. Anyways, here's our little virtual interaction:

Me: "Hey, I'm curious; how do you know my cousin Susan?"

Her: "Hello lol. I met her at an engagement party with an old friend of mine, and we became friends."

So I figure to open with something simple and advantageous since she's a very beautiful girl and I'm sure she gets a lotta AFC's that msg/add her, etc. Do you guys have any advice on how I should branch out in the conversation?

Also, I went through her fb to get a general idea of the people she deals with and her personality, this is what I gleaned: She's cool, down to earth -got that because she play talks gansterish, and also all her gfs say she's super pretty/sexy, and so do AFCs.

I hate Facebook. Don't read into that stuff too much - you'll sound like a creeper AFC if you search her profile for conversation topics. Just take the conversation naturally. You've already got two topics to go on (your cousin and the engagement party) and just lead from there. This is pretty generic stuff.