Always be prepared to hike out. In case your vehicle breaks down have with you a pair of good boots, a hat, a backpack and plenty of water.
Check the air pressure in your spare tire. Spare tires can lose air over time.
Carry a wooden plank or square of metal. This is to support your jack. In the event you suffer a flat tire (we've had two in ten years) the ground beneath may be too soft to support your vehicle. Both should be at least six inches square; wood preferably two inches thick; metal a half inch. A flat rock will also do but often one is not available.
Carry a chain. This is to pull you out in the event you get stuck (in mud, for instance). Though you may be in fairly remote territory often you are not alone. Don't be afraid to ask. Generally, people are happy to help. Strength of link is a judgement call; it will depend on the weight of your vehicle. Chains are also handy to pull away a rare fallen tree.
Check water depth when fording sinks or creeks. Our rule of thumb is: if you can't see the bottom always walk it first, especially sinks. Sometimes sinks have very soft ground layers.
Carry a camp shovel and hatchet. If you do get stuck (in sand this time, for instance) or decide to ford a sink that seems too deep you can build an impromptu ramp or bridge.
Carry a first aid kit and compass (if you don't have GPS).
Protect your gear or bedding from dust with a plastic drop cloth. Thinnest mil is best.