Oooo, this seems like a lot of work 😭. I don’t know if you’ve ever seen those PvP packs with custom armor models, but It would be cool if the armor had reindeer antlers. I’ve forgotten the name of the packs, lol..
Shading seems to be the most helpful tool whenever you're making a skin. There's no exact formula to it, but I recommend watching some Youtube tutorials to kind of get an idea where to start. When I started, @Jingles was who I usually went to for reference. Wish you luck! :)