In this point in the process, you've got a stack of books and articles on a topic so high it's frightening. Now what? Sometimes the hardest thing to do is read and understand what you've read, to get the big picture you need for the paper. When it's important to read and understand an issue well enough to synthesize everything you read, avoid plagiarizing anybody and most importantly give your opinion on what you've read, you might need a little help.
Find Your Place
First, set aside a block of time, two or four hours at least. Find a quiet, comfortable spot and scatter around you the articles and books you found during the previous background research stage of this process. Have handy a yellow pad and pen, and some way of tracking what you'll find without permanently marking the books. I like those little arrow stickers that Post-It notes makes in different colors.
And then dig in. Just read all of it through, take a few notes if you must, but plunge on through. I like to start with the most recent articles and work backwards. That way, you can pay attention to what references the authors use as basic research, and concentrate on picking up on recurring subtopics. Use your Post-It note flags when you see a topic that people seem to consider important. What are the interesting bits, the parts that different authors seem to find intriguing?
Scan for Important Details
You don't necessarily have to read every word of every article, or process every bit of information at this stage. You are reading to gain an understanding of what various people have already said about a particular topic, and to give you sufficient grounding in the topic to know what to write on.
When you're done, or even while you're reading, make an annotated bibliographic listing of each of the books and articles you've read. A listing of the author, title, date, publisher, and then a one or two sentence description of what the main point of the article or book was about, will help you recall what you've read and store it for later. By the way, if your essay topic is in your major field, you should consider beginning an electronic database of readings and put this information into it. But that's another article.