Most taxidermists would cringe at the idea of a hunter trying to prep his trophy in the field, but there are some situations where you simply can't drop off the whole animal within a few hours of killing it.
Here are a couple of tricks that aren't too difficult but can save your hide (pun fully intended) and help produce a high-quality mount once you get a chance to take it in.
Split the Nose: A properly split nose keeps pigment from discoloring during tanning. A good taxidermist will always be able to make a real nose look better than a fake one, so save yours.
Once you have the hide off the skull, use a sharp knife to split the cartilage of the nose right down the middle. It's tedious, but stay in the middle and you will eventually cut through and be able to separate and skin the two nostrils, allowing them to dry much quicker.
Turn the Ears: Start the process by hand, pulling on the ear cartilage and separating it from the skin while turning it inside out. Using a smooth dowel or stick to push from the inside is the most common way to do this, but every type of ear is a little different, so be careful.
As you push with the dowel, you will see the membrane where the skin meets the cartilage. Carefully cut along that line and the ear will gradually turn inside out.