Any advice with boy crushes?

How can I keep myself from crushing on guys that are above me in status..like I'm the quiet nerdy girl that crushes on cute frat boys then is dejected when they obviously mingle with hot sorority girls. I guess it's because I haven't had a bf or that special guy friend in a while so I try to fill that void. I also act and say stupid things around cute guys because I get really self-conscious! And how can you keep a crush from consuming your concentration? I'm kind of glad I don't go out a lot because then I wouldn't be able to concentrate on my school work if I was mingling and meeting guys all the time. Any advice?!