Are you studying Wuthering Heights in order to do a comparative essay? What my task will be come exam time is a comparative essay between Wuthering Heights and Mrs. Dalloway by Virginia Woolf.
Also, I think the most important thing is to know the book really well so keep reading maybe three times over should be enough. Then you should read criticism, there are a lot and many you can find for free online. There are really a world of information online, I think the hardest bit will be to sift through what is relevant. Best of luck!