Having done a TON of research over the past year and a half on speaker building, design and understanding measurements and how to make them, I can tell you there is a LOT more than first meets the eye. Making your own design, even if it is a simple 2-way is a very large project, especially for the beginner. There is a lot more variables then you as an audiophile would otherwise know of.
It is best to start with proven designs that are out there and to truely try to understand the list of objectives, concessions and benefits to chosen method. Then take this information for various differing speakers and correlate that with your own preference on the performance.
It is my belief that the physics limits us, at least at current, from doing all things perfectly, so we must choose which evils to conquer that we feel are the most hindering and try not to botch completely the others that are of lesser significance.
Every book on speaker building inevitably sticks to one philosophy and thereby is not complete. Ultimately the most cutting edge technology and understanding of speaker design is not covered in books, it is either locked away in IP of a company or is being frontiered by the most advanced DIYers paving their own road.
I feel the books are very helpful in gaining basic knowledge, understanding of measurements and their limitations. From there you try to gain understanding of your own philosophies and what you believe and then go about learning how to best acheive your goals.
It isn't an inexpensive venture! Measurement equiptment is not cheap, crossover design optimization software is not cheap (some is free but harder to use and generally not self contained) and proper tools for building speakers are not cheap. However, if it is a road you are very eager to travel, I think the fruits are quite beneficial. I think learning to DIY also helps you learn to see through so much of the fluff that is out there.