I seem to find that my navigational errors are usually at the macro, rather than the micro level.
For instance, I was walking in the Roybridge area last week, and we set off for Creag Pitrie. We got to the car park, and I headed off along an obvious 'track'. And stopped about 20m later and turned around. Then we wandered along the road for about 200m, looking for the bridge we knew should cross the River Spean. Then figured we were going the wrong way, starting from the wrong car park...
At this point, I decided I should probably look at the map, and figure out where I actually was, where I was actually going, and work out a plan to get there...
This is not the first such macronavigation incident; there's the infamous 'this is the wrong reservoir' (Blackwater vs Loch Eilde Mor) incident, where effects of previous night's celebrations, use of Harvey's map in urban environment, and the fact that we were all bimbling along chatting meant we didn't even look at a map until we got to the 'wrong reservoir'. Still, it was interesting, with such high winds that waves were blowing over the top and we turned back rather than even think about walking across the dam.
Once on the mountain itself, navigation was brainless, as you follow a landrover/quad bike track all the way up to the col between Creag Pitrie and Geal Charn (my mountain-biking friends loved it). At which point, micronavigation kicked in, combined with my usual terrain association/looking at the ground in front of me and deciding which way is the best up/down... Despite snow cover, freezing fog/low cloud giving about 50m visibility and howling winds, we headed off from a vaguish-point on a vague-ish bearing, only to encounter an obvious path as we worked our way to the summit, leaving the path where it became icy, and re-finding it again on our way.
Then, having got to the summit cairn and decided to retreat immediately, since Liz was having to crawl on hands and knees to stop being blown over, we fought our way back over the summit ridge and back down, again, on a vague-ish bearing, following likely-looking terrain. Only to encounter our outward footprints...
Now, if someone asked me how I'd done that, I wouldn't have a clue. There's something going on in my brain that is able to find 'the path', despite poor visibility and foul conditions that made it impossible to look at map or GPS. But I don't know what it is, or what terrain clues I use to do this.
So, the macronavigation lesson here is obvious; look at the map when you start, find out where you are, where you're going, and how to get there...
The micronavigation lesson? I have no idea...