I've been using black in the double bull blinds for three years now, anything else they can see, because their eyes don't operate like a camera. It is especially important to wear black on your bow hand, it's the first thing they will see if you don't, and if your bow has white overlay on the front, find something to cover it. If you wear glasses, they will see the reflection from them. I were even in warm weather a camo mosquito netting over my glasses, to minimize the glare.
Pastor Carl