Try not to think of PR as if you should already know everything in the material. I think that was one of my major problems. Approach the book as if you know nothing about it, like a beginner. Be curious about what you want to find out. Pay attention to any small thing you've learned. Go over the the book several times in 15-30 min sessions. Depending on how large or technical 2.5-3 hrs. should do. After that do a mind map. I personally don't like super-reading and dipping so I use rythmic perusal and skittering. Try all the different styles and see which allows you the most comprehension. Going through the material over and over is what makes it stick. It may seem slow at first, but after you get in a rythm it's far faster than any type of reading. That's just my 2 cents .

-Will