General rule is 10-15% the cost of the trip. If you have a guide that really works for you then I think it is only right to give him a bit more than the average. On the opposite end if a guide is just going through the motions or it is clear the outfitter is the brain he is the grunt than that is different, tip him whatever you feel comfortable with. Remember some of these guides don't make huge wages and rely on the tips portion a lot.

I would say you'll know what the score is and what is warranted. Have a good hunt and good luck!