Meditation helps you to get calm and relaxed. A good tool may be headspace.com.
Writing a regular diary helps you to keep track of your emotions.
Another Perspektive is always helpful by tackling stress, anxiety and anger.
Breathing is one of the most important actions of your life, and you probably don’t even know how to do it right. You have most likely heard that in order to calm down you need to slow down your breathing and start breathing calmly.
Talking to someone is never a wrong idea and sometimes it helps when you won't see the person again or the person knows how to listen.