Shovel would be my number 1.
Traction mats or sand-ladders, number 2.
Compressor to air-up the tires after recovery. Number 3.
Winch, number 4.
A good jack or two, number 5.
Pretty much THIS....in this order, when rolling SOLO. If I was to offer up any additional, it would be a new kinetic rope, over a kinetic strap. Prices have come way way down on some. They also have the benefit of being easier on you and your vehicle when either being recovered or when towing. Another added benefit is that they can be used more than a few times at one recovery, where as a kinetic strap has less pulls in it before it stops stretching.
Buy a bottle jack slightly bigger than what half your vehicle weighs (capacity). Make , fabricate, or buy a sand/dirt base for it. If you have a friend who can weld, make a V-notch or 3 sides channel piece welded to a cutoff pipe that fits over the jack screw, for a frame/diff cradle.
A winch is nice, but expensive. You can outfit everything on the list, and still have a lot of money to spare. I would move the winch up in the
list if you can afford it, as SOLO means alone. Depending where you are, it might be hours or days until you see someone else.
There are a lot of other stuff you could/should have if running SOLO. Check other threads here for recommendations, the above stuff is minimal.