This is just a simple guide to washing you guinea pig. But excessive bathing is far more worse then it is good. Try to only bathe them rarely, since they have natural oils in their fur. The cleaner you keep the cage, the less you will have to bathe them.
Step 1: Get Everything Ready
For giving a Guinea a bath, you cannot use human shampoos. Your going to need some Guinea Pig shampoo, which you can ask your exotic veterinarian for recommendations. You will need a large towel and a smaller one. And a small cup for pouring water. Then choose where you will give your piggy a bath, in a sink or bathtub. A bathtub is probably a better choice, so they can't climb out. Fill up the bathtub with one and a half inches of warm water.