How can I get become better at talking with guys? Help. 10 pts. (:?

I can pretty much interact and talk with any stranger out there, except for a guy i'm interested in. I don't get it, I turn into a blabbing idiot. Some reason whenever i approach a guy or even think about approaching a guy that im interested in my mind just goes completely blank. Usually I'm a real funny, Intelligent, nice, caring girl.. its just when it comes to guys i'm a moron. I've tried just throwing myself out there to get more used to approaching random guys but every time it turns out to be so bad its almost comical. I'm a pretty good looking girl, good style and all, I've even noticed guys checking me out but it still seems so far fetched for me to ever walk up and spark up a conversation. I know it shouldn't be like this but I don't know... it feels like their a million miles away or something. I'm becoming worried i'll never be able to do it successfully. I feel like i've let so many opportunities slip away just cause i'm so bad at talking with women. Its all I ever think about, guys, but its like i'm incapable of doing anything about it. I've had plenty of boyfriends in the past but the more I think about it the more i realize I was introduced through mutual friends and what not. I'm 19 now and its been about 7 months since i've had a boyfriend. What should I do? Any books out there I should read? Not books to help me pick up guys to sleep with.. just ones to make me more comfortable approaching a guy in a real situation. Anyone ever been in my situation before?