Myspace can be dangerous, but not facebook. :)
When you make your account, you don’t have to put your phone number down, or where you live or anything that you do not feel comfortable with sharing. Also, for any one to even become your friend (meaning you let that person talk to you and see your page) you have to OK them as your friend. Hope this helped :)
Facebook is not dangerous. People say its like myspace, but its a lot safer than myspace. myspace is a lot worse than facebook. (im allowed to have a facebook but not a myspace)
Facebook is only as safe as you make it. Adjust your privacy settings accordingly, and block people if necessary. I can't speak personally on MySpace, as I don't use it. Remember, Enjoy Yourself ;-)