Are you using too much product?
A lot of people think that more is better when it comes to shampoo and conditioner. That's actually not true. You only need about a dime size amount of product to wash and condition your hair. More than that is overkill and doesn't make your hair any cleaner or more illustrious. In fact, using too much conditioner can make your hair dirtier and weigh it down, while too much shampoo can strip your hair of extra nutrients.
Not only that - but it helps you save too. If you aren't washing that extra product down the drain, it will extend the life.