Well I know what you're going through! First off don't let them know you're scared of them! I'm in highschool, and it's all about power over other people to make themselves feel better! You should'nt care what people think about you. Remember all you need is one person who truely cares in the whole world! But why don't you just swallow your fears and walk up to her and say "Hey what's up?" Or if you're too scared to so that then be like "Oh I like your ... " that should break the ice. Then if she's like "Thanks...." then strike up so conversation from that.