They're over 30 years old and out of print but I couldn't think of better ones to cut your teeth on for the basics;
Linn Westcott's "HO Primer"
Russ Larson's "N Scale Primer"
Bill McClanahan's "Scenery for Model Railroads"
Linn Westcott's "HO Railroad that Grows"
And any Model Railroader magazine from the mid 60s to the early 80s. Each of these can be found on ebay for the price of new books.
There is something to be said for learning this hobby from the ground up, before everything was made for you. While true that many technologies are outdated, most all the new models, circuits and systems are easier for me to understand having known and been there during their development. Maybe I'm a bit nostalgic but, there isn't a problem you can encounter now that wasn't more carefully detailed back then and in a way that your average layman can understand.
Hope that helps.