So I must admit, I'm not a fan of online contacts but I have tried it before and have seen some success. The beauty with myspace and facebook is that you can contact a lot of people within a very short amount of time. Whenever I sent messages to women online, it was because I needed something from them. "I just moved here and I noticed you were into soccer, are their any leagues that you can suggest....."
Another method that I've heard is to create a false profile and put an attractive female's picture on it and wait to see what the guys message you. Then find a way to make it better. Not sure I'd take the time to do that but if that's all the resources you have then it might be worth a try.
Another thing that is very important is what your profile looks like. You can take advantage of the fact that she WILL look at your profile. Filter your pictures with only the ones that present the qualities that you'd want her to associate you with, so delete all the pictures of you passed out on the floor after a long night of drinking. Put up pictures of you doing exciting things, and throw in some with you around attractive girls (preselection).
These girls are messaged constantly, so you must set yourself apart and create a positive image that she would want to respond to.
Oh, and I always use lol or
to show that I'm joking around. I have also had many problems when I forget to include these, lol. You can always just tell her to calm down, the context was lost in translation.