Winch with a snatch block and tree strap.
Gun rack/case/holder of some sort that will keep rifle secure on rough trails.
Basic tool kit, including tire repair stuff, and low pressure tire guage.
I carry a small 12v air compressor and ATV-size jumper cables - they fit in the under seat storage on my machine.
Lots of bungees to tie stuff on.
I have rack extenders on the front cargo rack, make it easier to secure stuff.
Figure out ahead of time how you'll pack a deer out on your ATV. Be careful you don't add so much other stuff that you can't strap a deer on.
