Heat, moisture and friction can provide the perfect conditions for a blister. For athletes, blisters can be common in those who hold equipment for long periods of time—such as a tennis racquet—or those who spend a lot of time running.
The best way to help not get a blister is to have space between the skin and any object that could cause friction. Harder to do in the case of the tennis racquet but it is possible to choose clothing like moisture-wicking socks, or apply petroleum jelly/moleskin over an area where a blister is starting to form to reduce the friction.
When a blister does occur don’t remove the entire area of skin to get the fluid out—the skin will help provide protection and help heal. Instead, keep the blister clean, apply petroleum jelly to it and drain it through one small point but keep the rest as intact as possible. If there are any signs of an infection or if the blister seems to get worse make an appointment with your dermatologist.