Use low range anytime you are on something that is rougher than a dirt road. If you are on rough terrain, put it in first gear low and let the engine pull you along and blip the throttle anyting you need a little more to get over somthing. there is no need to apply constant throttle in 1st gear, the engine will keep you moving for the most part. The less you use the clutch the better. When you are going up a steep grade where you know wheel speed will be necessary (mud or lose dirt) put it in 2nd gear to get up the hill. For off roading purpose, you will never need higher than 2nd gear low range. It is also important to air down your tires so they can go over rock and logs easier. If you feel that you are going to stall going up a steep grade, do no push in the clutch, just let it stall. Start up the jeep in first gear with both your feet firmly on the ground, do no touch the clutch or gas and the jeep will start moving forward. It is important to not push the clutch in on very steep grades going down becasue you will lose control very quickly, pick your gear before you start down the hill and stick with it. The only exception is if you are going down a short very steep slippery grade and you start to slide sideways, you may need to puch in the clutch quickly to stop the side slide. sometimes if you are on a very slippery slope, if you are in too low a gear, it may feel like you are applying the brakes and starting to slide sideways.For wter and deep mud choose your gear before you go in and stick with your gear, no shifting in water, if you stall in water use the above method of starting in gear dsicussed above unless you took on water then do NOT start up your jeep, get towed out and figure out if water got in the engine.
sorry for the long ramlbling post but these are some of the off roading tips I can think of with a stick shift.
Steve, Olean NY, 2004 TJ Rubicon & 2006 LJ Unlimited