I think something that is glossed over in the Silva Method home study course by Nightingale Conant that is highly relevent to making the system work, and is also highly relevent to PhotoReading are the ideas of desire, belief and expectation. The Silva Method (and most other techniques of visualization for positive self change) requires that you remove doubts as to the efficacy of the system. Otherwise you are essentially saying to yourself - "I don't believe this works." and, in the case of learning systems, memory techniques, etc. if you do not believe it can work, it won't (although the converse is not always true). Essentially, you wind up defining your own limitations. This is also highly applicable to PhotoReading.
There is also a lot of power to be derived from "acting as if". Say that you are somewhat sceptical of PhotoReading or the Silva Method. Try acting as if the systems really work. Try to play as if you are getting all of the results that you want and expect. Then, after a while of playing like this (say, a month or two) see if you really do see improvements. You might take the stance that you did nothing more than talk yourself into making the stuff work, but if the end results are the same when you apply the basic techniques, does it matter. What I mean is - if you play "as if" PhotoReading really works, and you suddenly notice that you're getting results, doesn't that mean that there is a good chance that maybe it really does work? Similarly, if you play with the Silva Method and pretend that you can alter your moods, lower stress, etc. using the techniques of the system, and then after playing that way find that you are indeed getting those results, does that invalidate the system?