Having been an editor in a past life, the written word is extremely important to me in terms of directions and descriptions. Some authors lack the ability to organize their thoughts in an orderly manner and express them in a way that a new double knitter can understand. Of the two books above, the one by Baber is the clearest to follow. That said, however, Extreme Double Knitting offers much more "how-to" information. I find myself going back and forth between the two.
I started out attempting a hat in the the Post-Quinn book and after several attempts, threw in the towel. At that point I was not completely understanding that the results of my work on Side A was affecting by work on Side B. I ordered the yarn for the coat in the Baber book and decided to try that, as the pattern is worked flat. (The hat was circular, not normally a problem, but in double knitting it was giving me fits.)
When learning a new technique I usually begin by looking for Absolutes. Are there rules that apply all the time? There seem to be just two absolutes: 1. Every knit stitch is followed by a purl stitch and 2. Both strands of yarn come forward before purls and backward before knits, whether they are used or not. Beyond that, everything is up for grabs. Usually, but not always, the purl stitch is in a color that contrasts to the knit stitch, but not always; no absolute there.
The coat pattern is almost entirely in chart form, which is generally not a problem for me, but this time the chart is read from right to left, all the way to the left edge. The stitch at the left edge is called a Pivot Stitch, and from that point you work back to the right edge in the same row. OK. I get that, but every row is worked that way, whether it is a Side A or a Side B. Also, there is no right side or wrong side. Why? Because Side B is an exact reverse image of Side A, so actually the work is reversible. This requires transposing the chart on every other row - a requirement that I found challenging at first. In other words, when working on Side B, you are looking at a light-colored square on the chart and working a dark-colored stitch and vice versa.
Well, folks, that's it for today. I will continue the saga tomorrow. The bottom line is - thank goodness I learn by doing. It has all gotten easier.