If the matting is to the skin, then I would recommend shaving it. It doesn't take too long and is less stressful for the rabbit. Matting in harder to reach areas can be shaved out as well, this can be around the neck or belly.
If there are matts that are not near the skin and in an easy to deal with area, then you can carefully cut them out.
If the matting is not too bad, you can try brushing it out, but this can depend on the wool and the matt. Brushing out the matt can make it easier for matts to form in that area again.
To prevent matting, you need to brush out really well. Use a comb to get out little tangles and make sure yo get down to the skin. Many people will just brush the top of the coat while the fur near the skin gets matted. A slicker brush is good to help with matts that are forming to work them out. A fine toothed comb is best.
Using a blower is a good idea. A small shop vac with a blower will work as well. This helps open up the coat to keep it in good condition. If you don't want to use this, you can use a hair dryer on a cool setting to help find matts that are forming.