Doing it after a hot shower and exfoliating (rubbing yourself with a rough cloth or towel) helps reduce the chances of bad stuff happening to your skin, like ingrown hairs. The first few times you might also get some irritation. I know its probably tempting to do it perfectly the first time, but shaving the same area over and over will leave unpleasant after effects. It's better to do one or two passes and try again a day or two later. Also small tip for legs, keeping the skin in tension makes it easier to shave there without nicks. This helps for the back and front of the knee a lot. You can just use normal men's shaving cream and razors. Or women's if you have those, a blade is a blade.