Best shampoo for fine thin hair for frequent use without suplhates etc?

I have very fine thin hair - I need to wash it everyday as it gets a bit greasy on the roots and you can see all my scalp through my hair which I hate! I think it may be better to use a organic shampoo that has less/no chemicals, no sulphates, no parabens etc. I was thinking something from the Aveda range - or any suggestions? Please help!