There are some good blood trailers on here! I can only add one thing to this thread. The GPS thread made me think of it.
I always carry a compass with me even in small blocks of woods. (My good friends laugh at me for this) After the shot note the last land mark where you saw the deer and take a compass reading on it. When treestand hunting or in uneven terrain this is valuable since everything looks different down on the ground. Do as you normally would, find the arrow, look for hair, blood, hoof prints and begin trailing. If you get confused or there is no blood you can skip ahead to that landmark you got a fix on with your compass. Just go back to your stand and get a fix on it and go straight to it. If it is a good hit you should pick it up there or may help comfirm a miss. They may laugh at my compass but I have never been lost with it in my pocket and I have lost my bearings trailing deer and used it many times to regain my bearings, sometimes not wanting to believe it!

PS: Sorry guys, I see Steve McD covered the use of a compass/GPS in the original post 😳