I used to be into the offroad for many many years and my husband and I used to be trail guides. We would often have 'wheelin 101' trips for the beginners.
First & Foremost
1) Never go offroading alone. ALWAYS have another vehicle with you.
2) Stay on designated trails. Tread Lightly http://treadlightly.org/
In my experience in dealing with new folks.... Offroading is MUCH MUCH MORE than a drive down a dirt road. You will be driving over rocks, into gulleys, over burms.... and you CAN & WILL damage your truck. If you have any 'timid' thoughts about it - I would highly recommend riding shotgun in someone elses truck so you can see exactly what you're getting yourself into.
You need good driving skills & PAY ATTENTION to every aspect of what you're doing on the trails. Trails do not have shoulders, guard rails, or warning signs.
I once had a guy with a spanking new Dodge Power Wagon. He didn't listen to the 'helpful tips' that were given at the morning drivers meeting....and the guy drove down (off trail) into a narrow passage. His truck didn't fit between two trees. He ended up gouging half the side of his truck before even realizing what he'd done. We then, had to try and rescue his truck from further gouging. It was pathetic.
Just sayin.... (sorry, got off on a rant)