I don't know about textbooks, but before I start reading a book or watching a movie, I always go through a million study guides at the local library, and read about stuff on the net. That way, when I view the text, my understanding of it is coloured by the 'dominant' reading.
In terms of setting yourself homework, you could write down important quotes, a list of themes and ideas, and a plot summary if it's confusing - if you can be bothered.
It helps to be interested in english in itself, because you can add a lot of meaning to your life. A lot of the time when I'm not doing anything I find my mind wandering over things I noticed, in a movie for example, and trying to figure out what they mean and why they're there.
