There are hundreds of different types of shampoo available and a good deal of nonsense is written about their various qualities.First and foremost, a shampoo is designed to get hair clean. To do this the single most important ingredient of nearly all shampoos is a detergent to help loosen dirt and oil from the hair - if you try to remove them with water alone they will cling to the individual hairs and defy all your efforts.
When using a shampoo it is important to wet your hair first of all, and to rinse it thoroughly afterwards. It is best to wash hair under running water because it is easier to remove all the shampoo that way. If you wash your hair once a week, or less frequently than that, you might need two applications of shampoo. If you are washing it more than once a week, you only need one application.
Regardless of the many claims by manufacturers the best shampoo for you is the cheapest one that does not cause an allergy reaction and that doesn't contain any unwanted perfume. If you suffer from dandruff, however, then you do need a special anti-dandruff shampoo.
I don't think there is ever any point in paying extra for shampoos that contain beer, special herbs, vitamins etc. Certainly it is not sensible to buy a shampoo that contains a conditioner because to try and condition your hair at the same time as you are washing it is like trying to put your make-up on at the same time as you are washing your face! When you have washed your hair you need to be able to wash out all traces of the shampoo that you have used, before you apply conditioner. http://myshabi.blogspot.com/2008/10/things-to-know-about-shampoo.html