Make sure it's boiled, or fresh bottled spring water. Be wary of water in foreign countries. Your body adjusts to the chemicals and bacteria's in your local water. Depending on the country, the water may contain elements that your body will react badly to. Always boil, then refrigerate any water you are unsure of.
Exercise is something many people forget to do.
Keeping fit is the best way to make it through a show without getting exhausted. Competitions with the other band members can make it more enjoyable, and keep the band a tighter clicking unit. Some countries may have the medicine you can buy at any supermarket on their banned list. Speaking of doctors, if you are travelling over seas, make sure you have your shots. Some countries require you to have had shots before you are allowed in, and as some courses require a number of shots given over a number of weeks, get to your doctor early.