|Start simple and keep it simple until you have a reason to make a change! In general, this means that if you dry-pail you do a pre-wash and then a hot wash with very, very little detergent. Many of us have developed our own routine and you'll see some additives, like vinegar or baking soda, but I wouldn't even go there unless you think that you have a reason to.
I like to wash my covers with regular clothes at lower temps, since they don't need as much cleaning and I think benefit from the gentler treatment. Until their pee started getting stronger, I was able to just rinse my boys' covers out under the tap and machine-wash only once in a while or when soiled.