Reading Comprehension.

Hello,
Sorry for my post here, but I couldn't find any matching to my problem.
Okay, I have a problem with reading comrpehension. I'm Advanced level english student and I have difficulties with reading various texts. I get from 50 to 80% from each reading excersise and it makes me realy disappointed. I would like to improove it, but I don't know where to start, what should I know about this task type. Maybe you can propose any links, articles or anything, thanks in advance.

I've found this page: http://englishforeveryone.org/Topics/Reading%20Comprehension.htm - is it good to practise?

Thanks!