Ways to keep your colored hair not fade (i heard about washing hair with SHAMPOO and CONDITIONER)?

My friend told me that you shouldn't wash your hair too often (or at least with shampoo) cause it strips the color away, so I was wondering whether there are other things I can do to keep the color, I don't want it to fade before school starts. My friend also told me to wash my hair with BOTH (mixed together) shampoo and conditioner..., meaning instead of just shampoo wash it with both mixed together in a lather...I don't know if that will work, will it? I wash my hair at least 3 times a week so don't want color to wash away.Ways to keep your colored hair not fade (i heard about washing hair with SHAMPOO and CONDITIONER)?
The best thing to do is going to a salon JC Penny has a good one and get shampoo and condidioner with out Sulfate ... Sulfates in the shampoo and conditioner is what pulls the color out..They are more expensive but it keeps the color in longer.