Some interesting advice from the Collett's webpage:

Q. How do we know our trophies are well prepared and cured?
A. It is advisable that you bring with you adequate prepping tools i.e. surgical blades, skinning knives as this is Africa and there is a possibility that their equipment is not of the highest standard. Ask your professional hunter questions so you understand the procedures e.g. How far from skinning facilities are you hunting? If the hunt is far from any skinning facility you will need to prep your trophy and keep it cool to prevent problems.

Q. What are the best field care procedures we need to look out for?
A. 1) The professional hunter's vehicle needs to carry a container of water, a canvas cover to keep the animal cool, equipment for loading big game.
2) Animal must be washed of all blood on and around the wound as this can contaminate and cause hair loss.
3) Be sure of what you want to do with your trophy before skinning, so you can get the correct incision for your mount. Make sure you give your professional hunter clear instructions so he can implement them.
4) Be sure that when you offload your animal that you fill out and attach your labels. Make the start of your incision and attach your tag immediately. This will guarantee no mix up with other trophies.
5) Make sure you and the professional hunter check over your hides before salting. Make sure ears/eyes, lips are well turned and that they are fleshed off all flesh and fat.
6) Make sure trophies are well salted. Preferred salt to use is Medium Grain Sterilised Salt. Botswana Pan salt is not ideal for fur skins.
7) Skulls need to be partially cooked to remove all meat. Not over-boiled as this will damage horns and make them brittle.
8) Be sure that at the end of your hunt your trophies are well cured.
9) Make sure that your outfitter is equipped with adequate bug prevention for their storage shed.