The #1 cause of spoiling wild game comes from washing out the carcass or icing down the carcass. I know this sounds strange and counter intuitive but believe me in this matter.
My Father and Brother operate a professional meat processing plant and each year deer are brought in that have spoiled because the hunter washed out the inside of the deer or iced it down thinking they were doing the right thing.
The bacteria that spoils meat needs water/moisture to grow and do its damage. Without the moisture there can be no bacteria growth.
After field dressing your big game, drain out all of the fluid and then using a clean rag wipe out the inside of the carcass as good as you can. Be sure to wipe in every nook and cranny, especially between the hind legs and up into the throat area. Prop open the chest to allow for drying and cooling.
Don't skin your animal until you are ready to process the meat. The skin will protect the meat and keep it from drying out. If the temperatures in your garage stays at or below 40 degrees you can hang your animal to age for 7-10 days. If temperatures in your garage get above the 40 degree mark because of a warmer fall you should take your animal to a meat processor or process the game animal yourself right away. Just be aware that if you do not allow your deer to age for a while you will not have as tender meat. If you are going to be making all of your deer into hamburger or sausage the aging process can be eliminated all together. Another option is to quarter your animal and age the meat in a refrigerator.
You owe it to yourself and to the animal to properly take care of the meat after the kill. Remember, wild game is the best organic protein that you can eat. Check the price of true organic beef and you'll see that venison is a bargain. At least that is my story and I'm sticking to it :)