Well, I am not an expert, but this has worked for me so far.

I started out with books. For the essentials of joinery, both of Jack Sobon's books are excellent, as is Tedd Benson's first book. Jack also has a booklet of historical joinery that I also think is very good.

Then I took a workshop. I attended Jack Sobon and Dave Carlon's workshop at Hancock Shaker Village. This workshop is hand tool only, which suits me. Other workshops use power tools, if that is the way you want to go.

Then I came home and built the same building as we did in the workshop (a 14'x16' Dutch-style shed - I posted a pic in a different thread on this site). I also taught my brother what I learned. Doing this on my own really reinforced what a I learned in the workshop.

Now, I am working on an addition and garage. The addition is 16x26 and the garage 24x24. All the joinery was cut with hand tools and hand raised with the two of us and a gin pole.

Cheers,
Dan