Ok i recently accomplished this, and let me say its NOT easy.
First off don't throw a party, THINGS WILL GET STOLEN.
Ok now we need some more information, do you have friends, if so how many, how popular, etc... etc...
For me I had several friends in several different groups and some i didn't care for the group, so i started to move away along with another one of my friends. he then became friends with a pretty popular group. THey wanted to hang out with me, but it was hard to get in contact with them. I eventually had to start being around them and they eventually asked me to hang out. and now i'm doing stuff with them pretty regularly and let me say its awesome doing stuff.
Uhhh if you clarify your situation we may be able to help more