A muzzle, harness, two people (one to hold the dog still and one to cut out the matts) IF the dog a young dog. Older dogs can get stressed out and literally have a heart attack or stroke when groomed. (if your dog is overly stressed, take it to a vetrinarian groomer that offers the option of mild sedation) If you do it yourself, the easiest, least painful way to remove a mat from a dog is to use scissors and trim it at the base (be very careful to not get too close to the skin) THEN brush. Otherwise, you're brushing at tangles that tug at the skin and hurt the dog and can cause it to bite while brushed.
Talk to the dog about things it likes and keep a happy tone while you clip it. Half the battle is they are scared of scissors and razors, etc.. Take as many breaks as you need to to keep the dog calm and keep a dish a cold water close by(some get so upset they get themselves very thirsty very fast!)
Good luck!
(my least favorite chore!)
AOL Health