When writing essays, I've tried several strategies. I'll likely continue to try many more. I've yet to find one that works perfectly for me all the time. The first roadblock is always what to write about. What is the thesis of the essay? Often, the assignment will provide a general topic, but it rarely gives enough direction to even suggest topics. Sometimes it will dictate what specific scene you should write about, but not indicate any kind of stance to take.
Often, I don't completely narrow down the thesis right away. It rarely remains the same after several pages. It's good to get a primary direction in place, and then revise the thesis statement after part of the essay has been written. As the different arguments are made, there are multiple ways to link them together, and it is often the possible links which provide direction for the essay as a whole.
When reading the primary text, I've started underlining key phrases, putting boxes around other words, and making margin notes in pencil. I haven't yet decided on any concrete scheme for my markups. I'd really like to start a more comprehensive system of notes.
Often, I find it useful to write out single words relating to my arguments on post-it notes, and then arrange them on the wall beside my desk. I can then arrange my arguments in different ways, which improve the structure of my essay, and hopefully provide insight as to the direction of my final thesis argument.
I'm thinking about getting a small corkboard, so I can use strings and pushpins to weave a web of connections which I'm missing with post-its.