I used to use the apps on facebook to get talking to women, zoosk, are you interested and that type of thing, basically just as another avenue. Went on a few dates, some interesting! You just have to approach it the way you would meeting anyone new, treat the actual date as a blind date.
I met my girlfriend now after I spotted her on a photo of a mutual friend, her friend made her add me on facebook and I just found a way of getting chatting to her, we'll have been together 2 years on Tuesday!
So basically, use it for what it is, a simple tool to get to talking to single people, it's not a quick fix to a perfect relationship, but you'll get chatting to some cool people!