i would invest in a good undercoat rake for shedding periods, otherwise id head to a feed store and pick up a rubber curry comb (from the horse section) and a nice chameois cloth from the walmart car area.
the curry comb will loosen and remove dirt and dead hair without and stimulate blood flow to the skin. follow p with a good whipe down tieh the chameois to remove excess oils without stripping the coat.
A simple regular comb is good to have on hand in case of tangles but most labs dont need to be combed on a regular basis...
I use a rubber curry comb on any short haired dog i groom (and use it on dozer) and the coat always looks lovely and shiney but not greasy afterwards