If you plan on giving the cat a bath in a bathtub or sink, I would have someone hold the cat down while you put water and shampoo on the cat. if you try to do it yourself, if the cat has claws, he/she may try to hurt you with the claws trying to get away. Good luck with that.
Fill your bathtub with warm shallow water not very much. Have cat shampoo and wash cloth in use then place your cat into the bathtub and be gentle with them. Usually talking to them and patting them while gently getting them wet with the wash cloth helps. And by talking and patting them it kind of keeps them calm and try not to scratch you or jump out of the bathtub. And of course when they're wet enough gently pour some shampoo onto them and rub and massage it in thoroughly then repeat with squeezing water from the wash cloth onto them to wash out the shampoo. You just have to basically be very gentle and talk to them keeping them calm.
okay, this is a great question, i have had to do this a lot, you could either clean them with a warm wet towel or cloth, ooor, you could wrap them up in an old towel, and as in wrap up, i mean the back legs, or anything that could hurt you on his/her body, then just clean the desired part of body. so yeah, my friend was totally bitching to me about how this "will not work" well it will :) my cat has a problem with its booty, it like literally poops on herself, had to do this a lot! hope it helps!