Flat-coated retrievers don't need a lot of grooming. Their medium-length coats don't require much more than regular brushing, and their sunny, playful disposition keeps grooming sessions enjoyable.
Brush through your dog at least once a week with a slicker brush. This should be enough to keep tangles at bay and remove loose hairs most of the year. When you notice him shedding, brush him daily to keep the loose hair in the house to a minimum. When using the slicker brush, it is important to be gentle. The bristles of the slicker are metal, and, if used too aggressively, can scratch your dog's skin. The slicker brush does, however, do a good job of penetrating the coat to keep tangles from developing.
Go over any tangled spots with the metal comb and your fingers to work the knots loose. By brushing him frequently, you should catch any knots before they develop into difficult-to-remove mats.
Remove any mats as soon as they develop. With regular grooming, this shouldn't be a big problem; however, if your dog develops mats, use your fingers to pick the knot out, a small section at a time. Work from either side toward the middle of the knot, rather than trying to untangle it from the top or bottom. Once you get the mat loosened up, you can often get two or three teeth from the metal comb in and finish working it loose.
Clean out your flat-coated retriever's ears. It is important to make this a regular part of each grooming session so you notice any problems with the ears before they become serious. Use a commercial ear cleaner and cotton ball to clean out the ear. Never use a cotton swab, and never stick anything into the ear canal.