Make an effort with your appearance. Take a few minutes in the morning to adjust your outfit and your hair, and when you do get your hair cut spend a a little bit more than you usually do. Little improvements to your appearance will slightly change how you feel about yourself and how others respond to you, which will help you deal with your feelings of insecurity.
Exercise regularly. Endorphin release will make you feel happier, which will in turn make you feel more confident, which will in turn make you less prone to jealousy and anger.
Write three nice things about yourself on a piece of paper every morning. The process of doing this will make you think about what is good about you, which will make you feel happier and more secure in yourself and in your relationship.
Avoid intoxicants like alcohol. These dull your perception, which will make you jump to conclusions and amplify your anger, jealousy and insecurity. Alcohol is also a depressant, so you will feel even less secure the following morning.
Spend time with positive people. Negative people tend to bring one another down; if you are around negative people, talking constantly about how terrible things are, you will feel less happy and less confident. This feeling will manifest itself in anger and jealousy.
Count to 10 before you act in anger or jealousy. If you feel jealous, and are upset at somebody, remove yourself from the situation for 10 seconds. These 10 seconds will make you feel better as they will give you the valuable perspective you need to eliminate irrational jealousy.