This has probably already been mentioned, but DON'T BRING NEW BOOTS! You'll be doing LOTS of walking under sometimes heavy loads, and you NEED boots that are well worn-in.
Second, I always take a roll of bright yellow caution tape. Use it to mark the elk's location (and maybe a few spots along the way) if you will need to make multiple trips to get all the meat out - especially if you need to leave it overnight.
