I've tried a few of these, including the one in Derren's book. I have to say, none of it worked. Over the course of trying to remember 20 places of pi by various methods, I ended up committing it to memory too, but, and here's the important part, I do not remember them now. I think remembering different things benefit from using different techniques, and we just use the right one unconsciously, there's not a single method you can impose on all memory tasks.