Praise him with your voice and a good pat if he does good, scold him if he does bad. What kind of dog is he? I'm guessing a hound of some sort, they have awesome noses but they sure are stubborn! I have an 11 year old black and tan that I use to coon hunt with, he hadnt been in hunting of any kind in like 4 yrs and last weekend I put him on a wounded deer because we lost blood. I encouraged him and led him down the trail about 50 yds and cut him loose. I had to shoot the deer again, but he led us right to it. If it hadn't been for the dog we never would have found that deer.