Then take a look at the Curly Girl method.
Basically modern products usually contain silicones, which seal the hair and make it look OK temporarily, but need harsh shampoos to remove them when they build up. By using silicone free conditioners and styling products, and avoiding sulphate shampoo you can restore the hair's normal moisture. My curls are looking great, and I have kinks, if not curls right to the roots. Compare that to the flat top, and frizzy sides that I had before and you'll understand why I am so excited.
This method would work for frizzy dry straight hair too, although I guess the difference would not be as dramatic.