In addition to all the cool kits and pieces of gear that we can take along for safety, I think knowledge is the best thing to have. That and the ability to both stay calm, and then take action when prudent.
NWOL is great about sharing knowledge. There are people coming into Overlanding at an extraordinary pace. This means a lot of people with minimal experience and knowledge but great enthusiasm.
Check for classes - the Northwest Overland Rally is a fine place to take some GREAT classes that will enhance safety.
Our friends at Defenders Northwest host classes re vital skills.
On our recent trip to Douglas Creek, we had an unplanned winching session. Much learning was done re winching, traction boards, recovery straps and more!
Those with knowledge and experience, pass that on! Even gray-haired old guys like me have much to learn.
Perhaps we can add to this thread and share info, to help others be safe?
Safety around camp is one area I think where safety with knives, axes, saws and fire can never be taken too seriously.
Speaking about vehicle safety, I know I am bad when it comes to wearing my seat belt off road. I personally dont like wearing one at all, but off road is every bit as important as on road. Make sure all passengers are in and buckled before even starting the engine is another area I'm guilty of not observing enough.
As Guy mentioned, vehicle inspection and general maintenance are one area too often overlooked.
When traveling in a group, keep enough distance between rigs that you can watch their line of travel and make adjustments as necessary.
Also, make sure you can always see the vehicle in front as well as the one behind!