My process for reading a book is very similar to those mentioned already. To add to the discussion, I personally use a rating system in my books. I also write in my own books, so if you like keeping the books pristine, then maybe use Post it flags or something similar.
My rating system goes as follows; 1 Star = I either don't like the trick or it is something I wouldn't do. 2 Stars = interesting trick, probably didn't fly off the page right away, but I want to remember it for future reference. 3 Stars = Possible keeper. I want to learn this trick.
This will also help you track how much your interests change over time, which is just spiffy, in my opinion.