it is very much like war ; don't EVER be afraid to retreat , look at your 'attack' from multiple perspectives & if all of that and you still feel it is inevitably a win-less scenario, live to "fight" another day [ IOWs , choose your line, dedicate to it until you KNOW it is a bad idea and then back off , even if the other make it and you are being egged on. Take a winch and at least one of you should also have a HiLift. As the others said, no-no-no thumbs EVER in the steering wheel on rocks or in 4L or 4H ( it will become natural over time) and if you're wheeling stock, be hyper aware of high-centering and that flannel-thick oil-pan. your tires are vital and should be between 9 and 15 psi depending upon the terrain ( very approximate but any lower and you could lose a bead) . Don't follow too close and dont get too far behind. If you don't have CBs , setup basic hand or head/taillight indicators and whoever is next to last should watch the guy in front and behind him.
Freaking do not think you have a monster truck and try to ford water too fast or too deep and ( sorry) mud sucks.
Have first aid per the sticky on trail etiquette and most of all do not indulge until finished for the day. Besides that, and the repeating of all the other folks comments a second time, check your rig thoroughly afterwards and wash all the stuff out and off it before it dries.
I scared all my co-pilots away loooong ago and yet amaze them at coming home* with only trail pin-striping ( oh yeah; dont get panties in a wad about the scrapes; they are inevitable) and huge smiles on my face again and again. And, I take my DD up the trails with the SouthEastern rock-buggies & propane , square drive shaft truggies are flippin granite and limestone.... then I pass 'em and their trailered machines doin 85mph , headed home in the same rig I was climbing beside them with earlier ( albeit slower
) with..... Also, make sure someone knows where you're going that is not with you and the general time frame. Non JKURs might want to disconnect the 18mm Sway-bar bolts from the azxle mount tabs to allow for better ground contact to be maintained but maybe you will enjoy that first time your passenger wheel comes off the ground 4-5 feet in the air....
that , go beat the snot outta that thing and have a blast. Photos or we wont believe you.
(*yes; I am a rule breaker and *gasp* wheel alone; that means no one in pig with me.....I know the owners where I go beat my Jeep - AORP, Wooly's,BeasleyKnob, Windrock, Turkey Bay ,Uwharrie, blah blah....I have been doing this for a good while and do NOT advocate going alone if you value your life.....and Jeep and family....fwiw, I could drive a Jeep before I could ride a bike)