Just wanted to add my 2 cents... comments in your code -- and your code itself, generally -- should say what your code does, now how it does it. Once you have the concept of 'client' code, which is code that calls other code (simplest example is code that calls a method), you should always be most worried about making your code comprehensible from the "client's" perspective. As your code grows, you'll see that this is... uh, good.
A lot of the other stuff about good code is about the mental leaps that you'll make (definitely, if you pay attention)... 99% of them have to do with doing a bit more work now to spare you a ton of work later, and reusability. And also with doing things right: I almost always want to run the other way rather than using regular expressions, but every time I get into them, I see why everybody uses them in every single language I work in (they're abstruse, but work and probably couldn't be better).
Regarding whether to look at books, I would say definitely not in my experience. Look at APIs and frameworks and code conventions and other people's code and use your own instincts, and try to understand why stuff is the way it is and what the implications of things are. The thing that code in books almost never does is plan for the unplanned, which is what error checking is all about. This only pays off when somebody sends you an email and says, "I got error 321" instead of "hey, the app is broke, yo."
Good code is written with the future in mind, both from the programmer's perspective and the user's perspective.