While the greenest choice for shampoos is one that is free of sodium lauryl sulfate -- the chemical foaming agent found in almost every shampoo that is not biodegradable -- there are many people who do not want to give up their beloved hair care products. Instead, do the next greenest thing and wash your hair properly. Beauty experts agree that you only need a quarter-size amount of shampoo to wash your hair. The key is to use that small amount and bring it to a lather, massaging your scalp and working it from the roots to the tips of your hair. As for rinse and repeat? Forget about it.