Avoid heavy meals. This also means no alcohol, and nothing that might cause you stomach upsets. Bananas are a good choice, they are light and filling. It is also important to avoid taking decongestants or other medications that might make you drowsy. Use humor to help release endorphins.
Laughter is a great tension reliever.
Take some of the pressure off yourself by using interactive techniques. When you begin your presentation, plan to ask audience members a question and get them to raise their hands. This will take some of the focus off of you and put it onto them. Another way to help you relax before your presentation is to try simple stretching exercises. Perhaps the most important way to address and manage stage fright is to speak frequently.