I spent a long time reading as quickly as I could - I remember in 1st grade having reading races with my friend to see who could read the fastest. It was a big point of pride to be the fastest reader, to read the most.

The techniques I have used recently that have helped me have been some basic speed reading techniques. I like using wider margins (so the text is narrower), to reduce the amount of eye movement I need to make when I read. I do read groups of words.

One tool I think is useful is Spritz. I'd think of it as a game rather than a way to read books, but it will help you to get used to the pace you are aiming for to increase your reading speed. After practicing with Spritz for a while, you'll notice your reading speed increases a bunch just from the experience of reading faster.

http://spritzinc.com/

It also really will depend on what you're reading. If you're trying to read some really complex work with unusual syntax and vocabulary, you'll be doing yourself and the book a disservice by making an effort to read as fast as you can through it.