That's a level of thinking ahead I can get behind. I'll answer anon.
First thing, maggots. They'll eat dead flesh and you can't overuse them because no amount of maggots you apply are going to get the living flesh eaten. Note: Leeches are a bad idea. Do not confuse the two.
Second, you need to restore circulation. The idea is not to have your elf on life support, but to get the body healing on its own. If you can't do it, you're looking at a few missing limbs. A comprehensive solution will involve full nutrition and all the comfort you can afford. Massages are not off the table and remember: You're doing a good deed.
Oh—and they have to actually want to live.