I like all the suggestions of the above posters and use many of the same methods. To add to that, I've also learned to speed read by means of various online courses, videos. I was compelled to learn speed reading on account of another graduate student in my MA program who always impressed me with his ability to read all the material for each week with reasonable understanding. As a new graduate student I often felt overly rushed to keep up with the required reading and could only glance at some of the articles, essays, novels. This student consistently appeared to not only have read the material but was able to demonstrate this by speaking to it in classroom discussions with insight. His secret: speed reading!
Speed reading is wonderful for articles and essays, as well as general reading you might do online - newspaper articles etc. However, it's not as helpful in reading the types of novels you're likely to encounter in upper level literature classes as these novels are not written in the style or with the same sort of intellectual clarity as modern scholarly research. These novels are written as, well, novels and therefore tend to require nuanced, close readings to reveal their inner-workings and subtleties. As for novels, I try to do as much work up front as possible, such as reading through any appropriate wikipedia articles as well as any other summaries I can get a hold of. Afterwards, I use the speed reading method whenever possible while novel reading. All this is only for reading that must be done or self-study or something of general interest, meaning, I also do just sit down and read novels for enjoyment, wherein I take my time; however, when it comes to the pressure of reading for a class I can't recommend enough the use of any comprehension strategies one finds useful.