You may be surprised that we feel it’s necessary to talk about how to do something as simple as using a mouse. However, there are right and wrong ways of doing it.
When using the mouse, it is important to keep the wrist and hand in a neutral position. You want your hand to be positioned like the picture in the middle. This will reduce your risks of developing a cumulative trauma injury. The first two pictures below show bad form, and the last picture shows good form.
Another thing to be aware of is how much you are gripping the mouse. Keeping the mouse gripped in your hand the whole time keeps your muscles contracted without a break. When not using it, for instance when you are reading, put your hands in your lap. Also, pay attention to how hard you are gripping it. You should be gripping it like it is a raw egg that you don’t want to crack.