Re: land nav. help
Hey, I'm fairly good at this stuff but it is a deep subject and you should fare carefully because getting lost is no fun at all. But being able to go anywhere without getting lost is a priceless skill and worth learning.
For starters, I'd get the FM on land nav like stated above, that is a good place to start --master it-- some kind of 1/50,000 map to train on (preferably a map of your local area for practice, and a mix of city and some woods or desert would be ideal). A length of cord for notting, and a good compass. I like the Cammenga tritium model myself. I'd also invest in laminating the map and getting a set of Stadler map pens, the alcohol based ones with the eraser pen. Fine point. I'd get a plastic military compass and a strong piece of string, a couple of feet and a piece about ten or twelve inches to run exactly through the center of the compass.
The book is gonna teach you a lot of important stuff, like the three different norths, which one applies to you and how to use it or find it on your map, how to read your map, how use your compass (and I'm pretty sure they use the Cammenga one in there too) along with a lot of other tricks for if you get lost, how to do regression techniques, etc.
I was, and probably am, still good at it, but I've been doing it since I was a kid too, and I also have a good deal of math training. If you know some math, particularly some trig, you'll be golden. If not, you especially need that FM because it will give you shortcuts on lots of those formulas so you can take advantage of them.
GPS is fine and all, but DO NOT rely on that stuff! Case in point: I was issued an army GPS called a "plugger" and that damn thing just WOULD NOT WORK, day or night, and because they issued us those GPS units, we were required to get all 5 points of 5, instead of 3 of five at night and 4 of five at day. Anyway, I of course drew the longest, most protracted points through the woods, and in the rain day and night (night vision, even gen.3 PVS14's, don't work well in the woods in the rain with overcast and no moon!) I still was able to get all the points thanks to good map skills.
Good luck!