My navigation problems occur due to the following:
1. Vis decreases during dive.
2. Current changes or varies in intensity.
3. My mistake in identifying a natural object. For example, a large, and I think unique sponge, only to discover that an identical sponge is lurking 30 feet away.
All of these are operator error, but I have learned not to bumble around when I get that I ain't so sure feeling. If possible, I surface (allowing the obligatory safety stop)to locate the boat, and if I have enough time to return to the bottom, I do.
Maybe I just get narced easily, but I find it hard to focus on compass settings underwater. I can only manage by remembering just ONE compass heading and sticking to it at the appropriate point in the dive. Otherwise I rely on air consumption / mental map / landmarks to work out distance.
I usually insist on a good briefing on the boat, figuring out quickly at which point I am most likely to go wrong, and accordingly setting the compass heading for that rather than having compass headings for different directions or triangulating etc. . .sorry can't do it, would get completely lost.
For instance if they say fin towards the wall and then go along the wall north direction, I set my compass in the direction of the wall so that I can find it, presuming that once I'm there I will be able to go along it without getting lost. When at the wall I note a landmark (by looking backwards as I go along the wall) so that I will know the point to fin out from the wall for the boat.
If there is a crucial factor such as "don't go too far south or you will get caught in a drift and end up out at sea" I tend to keep that one fact in mind during the dive and get out the compass to make sure that doesn't happen.
In the beginning, you might forget about all the tiny numbers on the compass.
Just get used to N S E W, unless you use a slate and want to task-load out immediately.
Ask the boat crew to draw the bottom features on your slate before a dive.