As others will probably say, sound engineering is alot like being a musician or a photographer - you can read about it and I could recommend a couple of books, but you're dealing with soundwaves that you can't see, so you don't really know how to deal with them unless you actually deal with them. Musicians deal with the sound of their instruments (you have to learn how to play, then you have to learn how to make it sound good) and photographers are dealing with manipulating light to compose the perfect image - both activities mean you need the gear in order to learn how to do it. And you must put in the time to do it.
One book that I thought was a good basic primer was that book Mackie put out on how to run their mixers (the little 1202s, 1402s, 1604s, etc.) because it basically taught you what the mixing console really is: a signal router. And I forget the exact name of the book, but Mix Publications put out a book called "Sound Reinforcement for Musicians" which got a little more boringly in-depth. I'm sure there have been other books since then, but the Mackie one is really written for people who may know nothing about audio and I thought it was pretty entertaining to boot.
I think the best sound education anyone can do for themselves is to actually invest in a small system and start using it every chance you get. I know it's difficult, we're so busy buying stuff for our drumsets it's hard to justify another semi-large investment when you don't have the money, but getting your hands on the gear is the quickest way to learn how to do it. You could actually buy used stuff and save some money, but you'd be spending money nonetheless. I would recommend a little Mackie 1202, an effects unit, a power amp and a pair of speakers. Throw in 4 cheap microphones and you have yourself a nice little system that will teach you the basics of sound engineering, the Mackie manual even takes you through how signals get routed through the console (I don't endorse Mackie products but I have to admit they've gone more than out-of-their-way to teach folks how to mix and signal route!). Then you can be the person who supplies sound for family parties, church activities, etc.,. But the important part is that you're doing it. Oddly enough, if you get really good at it, you can actually get steady work doing it!