How do i talk to a guy :| And where can i meet them ? :|?

My friend and i are REALLY stupid. Like when i talk to a guy i think of him as my friend . And then suddenly like a week later some of them like me.. So i dont get it what did i do? Im really shy in meeting knew people but once i get to know them i dnt stop talking. So when i wanna get to know a guy i dnt really know how to .. talk and make conversation i get really scared and it suks. At the same time, if i think another guy is cute im jst normal around him and funny and dont really purposely flirt he tells me he likes me the next week. So how do i talk to a guy i barely know? And most of these guys re in school. So wheres a good place to meet new guys? And how do i talk to them.. What do i say ?!