Brush your dog's coat completely from head to tail before attempting to groom them. A slicker brush works well for the winter months, when your border collie is not heavily shedding. For the summer months, try brushing with a shedding blade first, which will remove loose and excess hair. Then brush with the slicker brush.
Remove mats using the mat splitter. If the mats are very thick, you can use an electric hair trimmer to remove them instead. This method also works well for dogs that are skittish and will not sit still to have mats removed. Simply run the trimmer across the top and sides of the mat until it is gone. If you still can't get the mats out, you'll need to cut the hair using blunt-nosed scissors. Cut immediately above the mat, making sure to separate your dog's hair from skin. Mats are often located in sensitive areas or close to skin, so investigate the area closely before cutting.
Trim excess hair around your dog's feet. Border collies are notoriously sensitive about having their feet touched. While scissors will give a neater, cleaner look, you may need to use the electric trimmer, which will work more quickly. Ensure that the hair is not growing over the ends of the toes, and remove any excess hair growing between the pads of your dog's feet.
Trim the hair around your dog's ears. A thorough ear cleaning and trimming should only be done by a professional groomer. However, you can gently remove stray hairs with your scissors. Check for mats behind the ears and, if you see any, remove them with the electric trimmer.
Trim the hair on your dog's tail. This hair tends to grow fastest and gets dirty easily, making it a prime location for matting. Excessive trimming will result in a bizarre, uneven look, so focus instead on removing hairs that are longer than the rest of your dog's fur and checking for mats. It's generally easiest to do this on the tail with the electric trimmers.