Remember to forgive yourself. We all make mistakes, don't we? Don't punish yourself through other means.
Remember that if you hurt somebody or their feelings, be responsible and accept that it happened. And remember not to be cruel to yourself - this happens everyone, you're not a bad person by any means.
Remember to replace the negative thoughts if you can.
Remember to release your tension in cliché ways and to not harm yourself in the process. For example, ripping up paper, scream into a pillow, exercise.
Remember to surround yourself with positive people. Not everyone might understand what has caused your anger, so it's good to be around some people you are close with. People you can look up to and talk to.