When it comes to essays, it's all about PEE. That's right. Pee.
If you follow those three steps, you can't go wrong. The best way forward is to merge one group of PEE into the next. I know when I write essays, I get all over the place with my ideas, and they seem a little jumbled when I reread. Just ensure that you blurt it all out in your first draft. In the second, rework the structure and ensure that it reads as well as possible. Your reader shouldn't be able to notice your PEE. If you've reworked it well enough, it'll seem as though your evaluation of one point has drawn your argument further along.
When it comes to said argument, you cannot lose with a schizophrenic approach. Argue one side. Argue the other. Argue a third, if you can find one. And then decide which you agree with, and explain why. You should have at least one quote reference from a secondary source (at graduate level, though it doesn't hurt to throw them in at lower level) per 100 words. This works out at an average, though. I'd say a healthy number of references stands at between 20-28 quotes/references in a 3,000-3,500 word essay. Use them like machine gun fire in your evidence. Make them believe you've done your reading. A good strategy for that is selecting quotes that are either chronologically far away from one another in the text, or selecting different texts. It always sounds better if you've mashed it up to prove your point.
Show some initiative. Markers get bored of generic answers. Even if you feel your idea is a bit out there, put it in - provided you can manipulate your quotes-collection to prove it.
I always go through the books first to find my references and group them into which argument they suit. It makes writing the essay itself FAR easier than it is otherwise. You want the process of writing your essays to be smooth, so that there aren't any gaps or jumps where you've had to stop to look something up.
I hope that helps. Let me know if you need any more.