Just carry a big hairbrush around and tell people that you will start swinging it if they don't stop messing with you. It works for me. Other than that, I pray, a lot (that I don't swing it someone). I yell when I'm in the car. Sometimes the windows are rolled up, sometimes not. I exercise to work out my pent up frustration. I walk, go for a swim, dance, punch a pillow, sing to a song on the radio really loudly. If you are old enough, then get a someone who enjoys having their *** kicked. Believe it or not, there are people out there that really like this. Take it out on them. If you really do a good job, sometimes they'll pay you. Crazy, but true. You will have to try a bunch of different things to see what works for you.
Meditation, yoga, exercise. Research shows it helps with negative emotions and the stress it can put on the body. Sooner you learn to deal with it the better. I am starting late, but at least I've started.
Reading helps a great deal