First get her to a groomer to get the mats out. They hurt her.and you could hurt her trying to get them out.Once they are out you can start by brushing her on a regular basis. A good comb is need too. To groom your cat start by brushing the part she doesn't like you to do.do this area first. then move to sides, then to the head and neck area. then last do the long strokes down the back that she likes, she will remember this and each time your grooming will be better for you both. Remember the tender areas are rear ends, and under the front legs. Some cats don't like their belly done either. be careful gentle and kind. Bad mats must be shaved out by your groomer. it will grow back.Cats can and do bite and scratch you if they don't like what you are doing.