There are supposed to be several good books on building guitars/basses.
However, I've never read a single one of them, I'm coming from an background of engineering and metal manufacturing for a living, I just started building them and used my common sense and metal working skills and tools, and of course the understanding of the underlying technical principles of what makes a guitar work.
EDIT:
[url="http://www.talkbass.com/threads/best-bass-guitar-building-book.305141/"]Here[/url] is a link to what some people are advising over on TalkBass.