Seek professional help
In my opinion, the best way to learn anything is to pay a professional to teach you the techniques and skills you need. Trying to learn on your own - it could take you years to encounter the siutations and conditions you'll run into some day - and how do you know you are learning the skills and techniques the professionals know? (not dropping the bike and breaking something isn't the correct answer)
Try the BMW Enduro Training program in Hechlingen (you can find out info online). Or, KTM also has such - I know they had training in Spain.
These people will teach you in the matter of a couple days most, if not all the skills you need to tackle whatever conditions you encounter. They know how to teach, and for the BMW course anyway, you will be taught how to handle certain types of conditions I have yet to encounter in my riding. The advantage is, when you actually do meet such conditions, you'll know what to do to ride it properly.
For these programs, the prices may seem steep (a couple hundred Euro a day), but you are using their bikes, and if you crash - well, you don't have to pay to fix the plastic bits. Do the same crash on your bike, and the cost to fix things up could very possibly be more than the cost of the program.
Afterward, you go out and ride as much as possible. Its a lot more fun than gaining knowledge slowly using the trial and error method of learning.
For old dogs who have bodies can't withstand the rigors of crashing, its the only way to go. Suggesting we get a small dirt bike and tear across the landscape is a sure way to break something other than the bike.
Chiang Mai, Thailand