From Shaving Made Easy, a book in the public domain I like to recommend to shavers new and old:

Purchase a good brush. The cheap ones are usually the most expensive in the end, and nearly always prove unsatisfactory. It should be remembered that the vital part of a brush is in the setting, and particular attention should therefore[Pg 46] be paid to that part of it. Cheap brushes are commonly set with glue, rosin or cement, which soon cracks and becomes unadhesive; whereupon the bristles fall out. We recommend a brush made of bristles or badger hair and set in hard vulcanized rubber. A brush so constructed, with wood, bone or ivory handle, and hard rubber ferule, will not shed the bristles or crack open, and with proper care will last for years.Do not leave the lather to dry in the brush, but after shaving rinse it out thoroughly and dry the brush with a towel, before putting away. The cup and brush should be kept clean and away from dust. Once a week they should be washed with hot water.

Today we have a great deal more choices when it comes to the materials used in the handle and in the glues used for the knot, but the rest of the advice holds true still – even if my cheap and cheerful Turkish brushes so far has provided fantastic value for the price asked.