How to throw a fundraising house-party?

I want to throw a pool party to raise money for WWF, world wildlife fund, as well as celebrate me and my friends end of school for summer, but i dont know how to...I had an idea of a change bucket but i dont know what else we could do to effectively raise money for my cause. I also could have them pay ahead but i feel that seems rude...HELP!!!!!! any ideas please?!?!?!