We built the house ourselves. We spent years reading nothing but how-to books; plumbing, wiring, passive solar design, and so on. By far the best book we read was called A Pattern Language by Christopher Alexander. It's a wonderful book, a good read even if you aren't designing a house.

 We hired and/or traded with other people for certain jobs, like the fine woodworking, which was beyond our skill level, and putting on the roof, which we needed done in a hurry.