This may just be a preference issue, but I would go with more books that are shorter in size. Topics that aren't too daunting and books short enough (300-400 pages) that a PhotoReading session doesn't take too long. I don't know if the analogy applies, but when I did programming, I would start out testing my work with a smaller collection of data. It allowed me to check results without long, drawn-out processing periods. Your conscious mind and inner mind are both learning this process (and to work with each other in a more collaborative manner), why not go easy on them at first? I guess my thought is that starting with shorter books allows you to get closure on a given book more rapidly.
I would go to the library and pick up arms full of general business or self-help books (or whatever suits you). Books that you don't have a big need to see results with. Putting too much pressure on yourself can interfere. Start with books that look interesting but which don't have a direct bearing on your work/career.
Notice when you've PhotoRead a book whether you think yhou need to activate. If you don't, move on. If you do, activate the book and notice how quickly you can move through it and gather the relevant information. When you're done, notice whether or not you feel the need to pursue the book further.
