How do you make friends?

[Gemma]

I'm 16, and I've really only got one good friend, I feel like the rest I'm just forced to think of as friends.
It's the new school year in a few days, and I want to be a more sociable person.
I've tried talking and being friendly, but sometimes I can't even be heard or say something interesting enough.
There is a group that I'd like to be friends with, and they have a few interests in common with me. My friend and I have hung around with them a few times, but they seem oblivious to the fact that I want to be friends. I kinda feel like I've already blown my chances with them. Do I say hi to them when I pass them? Do I ask to sit with them if the chance arrives? Talk to them on Facebook? Or will I become annoying? A few of them are in my classes, so that might help. What do I do?