I meant to post this a while back but forgot....The reason I found this out is because i've always had difficult seperating chroma and hue from value, many people do, although in some artists it seems to be an intuitive process. For me it isn't, and i've long been frustrated by it....Noone ever told me that there were tried and tested means of overcoming this basic problem.
It essentially lies in getting hold of a piece of transparent red plastic, or glass and looking through it. Most colours will be rendered a neutral shade by it and you can evaluate the value without getting sidelined by the colour or saturation.
Ta dah! I hope someone else finds this as helpful as I did.