I agree with the previous posters. I want to add, though, that the single most important thing about writing essays on literature is to really focus your essay on the work(s) of literature that you are discussing. Read the entire work(s) at least once -- more, if possible -- and select important passages from the work(s) to examine more closely. Don't try to talk about everything in any single literary work. Focus your topics, develop your discussions, and support your generalizations or observations with evidence from the work(s).
Focusing primarily on the text doesn't mean, of course, that you're forced to adopt a New Critical approach and talk only about the text. You could talk about your personal reactions to the work(s), based on your own background (this approach might be called Reader Response), or you could talk about how the text mirrors some of the major concerns of the time in which it was published, as these concerns are reflected in newspapers or other media of the day (this approach might be called New Historicism).
There's no one way to interpret and write about literature. The main thing to keep in mind is that understanding the literary work needs to be the main focus of the essay.
Here are a few points to consider.
1. The most important point is that you need a purpose for writing. This is called a thesis. The better the thesis, the better the essay. You should spend a good amount of this on this point.
2. After you have a thesis, make sure you have good reasons for why you think your thesis is tenable. If you can't think of good reasons, go back to step one.
3. At this point, you could also start looking for good quotes to grab the readers attention. However, use quotes sparingly and only when they work in your argument.
4. Think also of counter arguments. I am sure that not all readers will agree with you.
5. Finally, keep in mind that the writing of essays is never a first time finished project. You will need to reread your work and rewrite. If something does not work, without mercy, cut it out. Great writers, (all of them) revise and then revise some more.
Whew! HUGE question here. I'll get you started.
Here's a list of things you might wish to consider when writing a literary essay:
1. Writing is a recursive process. Very rarely will you write something that is near perfect the first time. You must go over and over and over your papers.
2. Use the writing process: a)brainstorm, mind-map, amass quotations; b)prepare an outline; c)do a first draft; d) revise, edit, or get someone to help you proofread; e)revise and edit as many times they're needed.
3. Quote for demonstration and effect. Do not think that the quote speaks for itself. Don't just plop them into your paper without commenting on them.
4. Enotes has a good essay writing resource. Search the essay "writing lab" and you'll have a tonne or resources. Do a website search for more. The owl writing center at Purdue is another fabulous source. A classic book you might buy is Writer's Inc--a fabulous resource that has examples of everything!
5. Become familiar with the Modern Language Association's style of formatting and documentation.
There's much more, of course. I'll see if I can dig up more resources for you.