Tough books to read to improve reading?

I'm not sure if this helps. I'm a student, and I read slow and didn't understand well in the past. It affected my study quite a lot. Since reading occupies quite a lot of my time every day, I've tried to read more difficult books but that just didn't help much, so I believed I need to find some other way to improve my reading skills. Finally, I followed some speed reading course and it worked very well. Now I do much better in my study.

So instead of books, I'll suggest you to look for some speed reading course to learn with, it is the formal way to improve reading speed and reading skills. You must practice with some tools provided in course, or it could be quite difficult to pick up those skills.

I can recommend the course that I've used for your reference too. I chose it at that time because it has quite a lot of good user feedback, and it is affordable. And it covers reading speed, reading comprehension, and memorization skills. There is also a website which tells how to get the best out of the course, and it guides me to choose the online version of the course. I put the links here for you to check them yourself.

http://www.amazon.com/gp/redirect.html?ie=UTF8&location=http%3A%2F%2Fwww.amazon.com%2Freview%2F0977476006%3Fie%3DUTF8%26ref%255F%3Dpd%255Fbbs%255Fsr%255F1%255Fcm%255Fcr%255Facr%255Fimg%26showViewpoints%3D1&tag=moreinfo-px-20&linkCode=ur2&camp=1789&creative=390957

http://speedreaderxreview.com/

Hope it helps :)

I highly recommend this fantasy book for vocabulary: Perdido Street Station by China Mieville

Twilight and harry potter are not tough to read, nor do they improve your reading skill...(but they're fun..)
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If you REALLY want to get a tough book that would help your reading skill then read some of the older great literature (the original version) like a "Tale of Two Cities" "Moby Dick" and etc.

twilight series and harry potter series