Sorry to disagree, but the fieldcraft should be 80% (or higher) Camouflage can not make up for bouncing round the countryside like a bull in a china shop.
Birds are a different matter, deer can be approached using cover and dead ground, in the open steady stealthy movement will get you there.
I have never covered my face, except when the midge are intolerable, and have never had a problem that camouflage would have solved. Deer notice movement.
PS I do not wear real tree or anything similar, as I feel it is not required.