With a Fine Toothed Comb!
So how were they used?
If you look at Roman paintings you find neatly combed hair in both men and women. In later Saxon and Viking times you can again refer back to the helm plaques at both the finds at Birka, Vendel and Sutton Hoo. You find warriors with neatly combed shoulder length hair.
A very fine tooth comb was used to remove fleas and is often called a "nit comb". The expression "go over with a fine-toothed comb" meaning "to search out in minute detail" comes from these combs. It took a lot of time and care to use a "nit comb"
A comb must have been a necessary part of any good Viking, Saxon, Roman kit!