This topic makes me feel all fuzzy and warm! I suppose you have the power to do that, Kilala XD
Hmmm, I only have a few things I look for, but they are very important to me!

Kind/Loving/Sweet
However you view it, being a kind person is good in any friendship :3 Being able to listen to other people and help them out is also part of kindness, I believe.

Humor
Who doesn't love to laugh and make people laugh? It doesn't even have to be alot, it just has to be tucked away somewhere in a corner of your heart for it to mean anything ^.^

All around good person
No, you don't have to be a total angel, but at least be someone who is intelligent, knows right from wrong, and won't do stupid stuff just to get attention. I would hate if one of my friends got hurt ;.;