I would give it a good wash first with Dawn then wet sand it. I would then give it another good wash with Dawn. There are some firm believers on this board who use Ajax to clean before painting. I would save the wax and grease remover for the last step and use new clean paper towels designed for the process. Some cheap paper towels could very well be contributing to your problem. Another thing about tack rags. When and if you use them do not press down on it with the palm of your hand as you wipe. Just the weight of the tack rag is all that is needed, just pull it across the surface, don't rub it.