The phrase "trail etiquette" can mean a lot of things to a lot of different people. In this post for beginners, I talk about being a part of a group and related guidelines for being a good participant. These are just a sample of the basic rules to wheel by.
TRAIL COMMUNICATION IS A SAFETY ISSUE: Trail communication between vehicles is not just a convenience but a safety requirement, IMHO. The ability to communicate with others that an obstacle is still blocked or has been cleared or that a hazard is present can save a lot of grief. Knowing others are on the trail, such as hikers, horses, or ATVs, can be important for the safety of everyone on the trail. Whatever your group uses for communication, be it CB, HAM, GMRS, or something else, get one and learn to use it.
YOU ARE RESPONSIBLE FOR THE RIG BEHIND YOU: You are responsible for the vehicle behind you when traveling the trail or in the convoy to or from the trail. You should try to keep that vehicle in your rear-view mirrors as much as reasonable. If they move slower than the group and fall behind, you should slow down or stop as needed for them to catch up. The driver in front of you should see that you slowed down or stopped and do the same AS WELL. Nobody will get left far behind if everyone does their job. When you come to a fork or turn in the road, you should wait at the intersection until you know the driver behind you sees the turn. They will make sure the same happens for the rig behind them. If someone needs a little privacy, you can't always keep them in view, but you can keep them in radio distance or sit just out of sight and wait for them to rejoin the ride.
GIVE PLENTY OF SPACE BETWEEN RIGS: A little bit of space between rigs is a good thing. Whether the rig in front of you is moving or stopped, you should not run up close behind them. Among other things, a little distance allows you to see the trail more clearly so you may see and choose the better line. When going uphill, staying back may keep you from being hit by rocks that are tossed or rolled down by the vehicle ahead of you. They may need extra room to back or deal with obstacles. That will be much more difficult if you are right on their bumper. On really rough spots, wait at the bottom or top, as the case may be until the leading vehicle clears the hill completely. If you cannot SEE them clear the hill/obstacle, call on the radio and ask if they have. Make sure you let others know when you clear a blind obstacle too.
THE UPHILL DRIVER HAS THE RIGHT OF WAY: The general rule is a rig going up a hill has the right of way over those going down. In many cases, a rig going uphill must maintain momentum to clear the obstacle. If stopped mid-hill, they may have to back down and start again. It is "best practice" to move over, wait for them to clear the hill, and then proceed. The exception to this rule, like most exceptions, requires a little common sense and some common courtesy. If someone is sliding down a slick or icy hill or is on an obstacle they cannot stop on or back up on, give them the right of way, regardless of their direction.
DRINKING IS FOR AFTER THE DRIVING IS DONE: Just don't do it. Drinking puts everyone on the trail in danger. Drinking and driving is not just dumb, and it is illegal. The laws are the same as when driving a trail, in town, or on the interstate. Having an open container in a vehicle is illegal in all states west of the Mississippi River. This does not change because you are in the forest. Off-roading is challenging enough without being drunk or high on the trail.
ONLY FRIENDLY PETS, PLEASE: It is simple. If your dog is dangerous to people or other pets, leave Fido at home. I have seen a few people quickly wear out their welcome due to an aggressive pup.
BE KIND TO OTHERS YOU MEET ON THE TRAIL: Share the trail. Move over when you can and give motorcycles, ATVers, and faster-moving folks, the right of way. Move past hikers slowly, don't kick up any more dust than you must, and be friendly. If you encounter horses, move to the side of the road and turn off your engine. Some horses are pretty skittish, so ask the rider how best to proceed if needed. If you have to pass horses, go slow and keep the engine as quiet as possible. It should go without saying, but no revving engines and no horns, please.
MEN TO THE LEFT BECAUSE WOMEN ARE ALWAYS RIGHT: This is not meant to offend anyone. It is just an easy way to remember the rule. When the group stops in a spot without facilities, this is a good rule of thumb to prevent conflicts in the bushes. Please remember to bury anything left behind at least 6" deep or, better yet, pack it out.
EXCEPTIONS: Rules are good things, but sometimes safety dictates an exception. These rules are not set in stone for a reason. An experienced off-roader will know this and adjust as needed. As Captain Jack Sparrow's pirate crew might remind us, "These rules are really more like guidelines, anyway." Knowing the rules is important, but learning when to use a little common sense and adjust those "rules" to the situation, is a sign of experience. Remember, there is just one unalterable, never-changing rule in off-roading. That is SAFETY FIRST! No other "rule" is more important than that one.
Of course, there are always more "rules" one can add. However, this is a good start. Ultimately, it all boils down to one simple phrase: BE FRIENDLY, BE HELPFUL & BE SAFE.