They should be tended to as quick as possible as bacteria sets in the moment death occurs.
Cool as soon as possible, when considering on having a specimen mounted. Blood should be removed as much as possible.
Don't cut the throats of any animal to allow it to bleed out. Just a typical field cut is all that is needed to remove innards on large game.
When dragging, protect the front shoulders, or if it is a life size mount that you are going to want done it must be placed on a drag sled or cart.
Do not make any cuts on fish or birds, place all waterfowl on their backs so the belly is facing up, the feathers are so dense in that area it does not allow heat to escape, and the intestinal fluids pull to the lower area causing a rapid growth of bacteria and as a result feathers will slip.
These are the basic simple rules to follow.
Please feel free to call if you have any questions concerning a specific type of field care.