This question plagues me as well.

I am lonely and I want to meet new people, but I don't want to meet new people just for the sake of meeting new people. For starters, these types of friendships tend to be very ... uhhh... 'vampiric'. Meaning, I'm only friends with them for what they can give me. In most cases, just a warm body who will listen to my problems. I find these friends are very understanding until they realize you're just talking to them for your own ulterior motives.

It also makes me very sensative to the things they say. If they even hint at a criticism, I get very defensive. It's very unbalanced. I also find I go places to find friends that I don't normally go. When I'm back to feeling 'normal', I stop going to these places and lose all these new acquaintances or friends. There are so many things are not ideal with looking for friendship when you're emotionally unstable. It's dishonest in a way. You're not who you really are.

Looking for friends when you're lonely is the worst time to find friends. It's like going to the grocery store when you're hungry (you end up with a lot of food that you have to eventually throw away). I just think the key is, and I'm only speaking for myself, be happy with who you are and be content with being alone.

This is hard.

This is very hard.

Ideally, the best time to make friends is when you know yourself, are comfortable with yourself and can give and receive in healthy ways. Everything else will just end badly. Having said that, if you really want a quick way to simulate a friendship, find an online penpal or someone in a chat room. At the very least, they're tolerable distractions.