If its just a depressive mood... I try to read something, watch a movie and if its late enough I go to sleep early. Its easier to look at the problem if youre emotionally a bit more calm.
Also I try to talk to people I can talk seriously with. Be it online or Real Life does not matter. Hanging out with friends is good to. It also does not matter if you talk about your problems or not, as long as you dont talk to some trolling moron. Somebody who is on the same wavelength is perfect.
Next possibility: "Fuck the Pain away!" (Peaches). Find a chick. Fuck her brains out. Does not always help. Is not possible for everyone. Sometimes youre too young. Dont pay for it! :O
Oh and, a few words of advise:
- Dont drink alcohol. Burning your braincells is not worth it.
- Dont smoke when you are alone. It can lead to psychosis (I can tell...
) and dont smoke too much/often. I need only a little to feel "light" and I like it that way. If you got buddies with you you can talk about shit or play cards or stuff like that. You will most likely not start to think about your problems.
Most other things are already said by people that are not obviously moroning around. ;)
Good Luck!