This is an excellent question because facing the plethora of haircare products on the market can be bewildering. The answer depends on your hair type. If you have curly and relaxed hair, both a conditioning shampoo and a separate conditioner should be used because the hair requires concentrated conditioning to reduce friction between the hair shafts. But if you have straight and fine hair, the use of a conditioning shampoo and a conditioner will leave the hair limp and difficult to style. As a general rule, the curlier the hair, the more conditioning required; the straighter the hair, the less conditioning.