There's a lot of things like playing games or watching television that helps relieve stress, but singing a tune or two always clears my mind and feelings. It's a great reliever for me.
I don't, unfortunately. I just kind of go with the flow. You could say I deal with (school-related) stress by getting my homework out of the way faster and in a more efficient manner.
Well, my old teacher/advisor used to say that the first thing you need to do is BREATHE. Just sit for like 5 minutes, and let the only thing you think about is your breathing.
On a similar note, try meditating. That can really work wonders for me, so maybe it'll work for you.
Unfortunately, I usually do what Ron does, like 97% of the time.
I also recommend listening to music, taking a nap, taking a shower, playing a sport, playing video games, watching your favorite TV show, hang out with your friends, draw a picture, write a story, talk to a friend (actually very helpful), and more! I sound like an infomercial :x
And one thing I usually do (although I normally do it when I'm trying to fall asleep) is come up with a story, and pretend you're the main character. I often give stories to video games that don't have one (for example, I once gave a very odd story to cooking mama)