Learn positive ways to express your feelings and desires to people who may be causing you stress. If talking to a person isn't the answer, then put your feelings on paper in a journal. Many times the simple act of getting it off your chest in an appropriate manner will reduce your stress level. Surprisingly, much of the stress you experience daily could be due to what you are putting into your body in the form of chemicals. Be sure to eat a balanced, healthy diet to assure you're giving your body the nutrients it needs to operate and maximum efficiency.
Caffeine is a stimulant.
If you drink more than a couple cups a day, try decaf. You may find that switching to a good decaffeinated coffee will reduce a significant amount of stress. Alcohol in small doses may help you relax. However, in larger amounts it may increase stress as it disrupts sleep and causes hangovers. Large amounts over an extended period will start damaging your body.