When you do get representation you don't want to be the whore of the internet, you want to be professional, on time, and prepared. Although these social sites all say, Sign up! Be a model today! Hurry, hurrry! I would not do it.
I think the more you interact with real people, real agents, and not just internet encounters the closer you will be to real agents, real modeling jobs and real opportunities.
Yes there are great sources on the web, wonderful ones, but only relying on social media tools can bring a real let down to girls who are looking to be models, the real jobs are being cast and you don't know about them because you do not have a respectable agent, or a compcard, or headshot, or a modeling portfolio.
You wouldn't try to be a doctor with the education right? Same with modeling...don't sort of try to be one, so to really be one, you need to think like a professional. Legit modeling jobs are happening every day, but they are not looking for newbie models, wanna be's and so-called models on the web. They are calling modeling agencies.