Some great tips on here already, but just to add to the "slow down" tip.... If you have spent a long time sneaking into an area you saw a buck, don't give up because he isn't in the same spot anymore. I don't know how many times I blew an opportunity because I gave up 5 minutes early. I would think that there is no way he is there anymore, stand up to look around and BOOOM he busts out 20 yards from me.