Here is a great video produced by Land Rover in the 1980's on how to drive your Land Rover 90 or 110 off road. Although the video concentrates on the 90 and 110 (Defender) models, this video will also apply to any manual Range Rover of the same age.
It covers every obstacle possible, from side slopes, to water crossings, and even includes reversing with a trailer. There is a handy graphic on screen which shows which gear the Land Rover is in, whether diff-lock is engaged and if the gearbox is in high or low ratio.
The video compares two V8 Land Rover 90's (affectionately known as "red" and "white") and each demonstrates the right way, and the wrong way, to drive off road. In addition they also compare the off road ability between 205/16 and 7.50/16 tyres, and how different gear selection is important dependant on the tyre size.
To complement the video, here is the list of past articles we have written on driving off road in a Land Rover.