I haven’t done much decomp myself, but here’s my advice for doing so. If you’re keeping your finds outdoors to process, make them as inaccessible from scavengers as possible. Leaving them out unprotected will only attract animals that will eat, chew up, and carry away your find. My favorite method, (and one I’d like to try this summer) is bone-lustdecomp box. Burial is also an option. If you’re going to used the burial method, keep the animal bagged up as to prevent the loss of any smaller bones, and make them easier to collect later on. Jake’s Bones has a guide for different methods of how to clean animal bones, including burial, dermestids, and maceration. If burial doesn’t seem to be working out the way you want, any of these methods will work just as well and may be more convenient for you.
As far as how I go about wet specimens, I just grab a jar, put them in, and pour some 70% isopropyl (rubbing) alcohol you can buy at any store with a pharmacy section. The downside to this method is that the specimen will lose it’s color over time. Another recommended way to go about it, is to use both formalin and alcohol. To do so, the specimen should be injected and submerged in formalin for about a week, left in water for about a day to leech out some of the formalin, then placed in jar and displayed in alcohol. Here’s a few sources that go into more detail include the warnings and health risks of working with these chemicals:
Something in the "loam" category is my first instinct. Note that I don't actually know what "loam" is, but I get this feeling of like, kind of spooky dirt that's also comfortable and soothing like home so. That.