I have always encouraged amateurs to get some training from a working professional if they are serious about this business; there is just so much to learn from the day-to-day and so many things you just don’t think to put in a book.  I recently bought this book and am looking forward to reading it (this is the first volume- Design) as it deals in the theory of making a great guitar.  I am often dismissive of the worth of things like this but in this case I have seen that the author really has a lot to offer about how wood and sound work together.  If something good comes out of reading it and using it then (just as with good tools) the price is well worth it.  Find it here.