The thing which really worked for me was genuinely getting lost with a (hung over) instructor sitting next to me, on my second ever navigation exercise. The instructor apologised the next day, and I never flew with him again (he wasn't my regular instructor anyway) - but seeing an instructor reading from ground to map, exactly like the textbooks say, really helped hammer home the technique.
In our case, it wasn't too difficult - there was a large town a little way in front of us, which we figured was probably Oxford. Having done the "reading from ground to map" bit, we then continue to positively identify it by reading from map to ground, and confirming that roads were where they were supposed to be, and so on.
Knowing at least roughly where you are is a big help. Always keep an accurate flight log. If you change heading (maybe because of a wind correction, or because you'd forgotten to align your DI with your compass and got off track) then write it down, and write down the time, too. Then, when you establish that you're lost, either continue on your current heading if you're not concerned about airspace, or else pick something on the ground and begin to circle around it (after noting down the time!) Then, if you can't spot where you are quickly, you can use your flight log to help you figure it out.
(The way we got lost was by making a relatively large adjustment to our heading because of what we thought was a bad wind forecast. It turned out that the wind forecast wasn't that bad, we'd just mis-identified a landmark and so interpreted our position incorrectly, so our heading change had actually taken us well off track. Knowing the heading corrections that we'd made, it was relatively easy to figure out the area in which we thought we might be, even though it was some way off our planned track.)
One other thing to remember - not too relevant for practicing the lost procedure, but very helpful when it comes to real navigation. If there's really nothing around that you can use to confirm you location, don't worry. As long as you flying the right heading for the right amount of time, you'll end up roughly where you want to be. If you know you should be able to see a large town in 10 minutes time, then just keep flying until you see the town - and once you see it (which you will be able to, even if you're slightly off course) you can assess whether you need to make any corrections or not.
Have fun!
FFF
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