Some Tips for Writing In-Class Essays:
A. Try to write fairly loosely. In other words, make sure you organize your essay and have an introduction (complete with thesis sentence) as well as a conclusion, but don't be so worried about organization that you forget to leave time to express and develop your ideas fully. Unlike with out-of-class essays, err on the side of more rather than less.
B. Remember that your in-class essay should have a brief introduction (not as long at the intro. for an at-home essay--two or three sentences will suffice). Also, the final sentence of your introductory paragraph should be your thesis. This thesis doesn't have to be perfect but it should give a definite idea of the argument you're going to make in the body paragraphs of the paper. Be specific--don't make broad statements that don't really say anything.
C. As always, make sure you refer to specific scenes, passages, and lines. Your body paragraphs should each have at least two references to the text. Direct references are generally better than paraphrases, but don't spend too much time looking for a quotation.
D. You will be able to use your text and I encourage you to mark it up so you can find appropriate quotations to cite quickly and easily.
E. At home, you might prepare by reviewing passages and notes you've marked. As you read through the marked passages, think about recurring ideas, character traits, images, and themes.
F.Try to come up with sample essay questions at home. Think up your own questions and answer them in a timed situation or use someone else's question from the class conference site. Even if the actual essay question is rather different from the ones you answered at home, you will find yourself able to answer the question more thoughtfully and deeply as a result of having read the text actively and having thought about it in detail.
G. I recommend preparing a brief outline before you begin writing. Do not, however, spend so much time on the outline that you have to rush to write the actual essay (no more than 5 minutes on the outline, as a general estimate).
H. You might take note of key passages by placing a "sticky" in the text so you can find those passages more easily.
I. Avoid using the phrase "there is." For example, instead of writing "there is a conflict in this poem between the speaker and the poet that illustrates the irony of the poem's dramatic situation," write "the conflict between the speaker and the poet illustrates the irony of the poem's dramatic situation."
Note: the above are just suggestions based on what has worked for me and for some students I've worked with in the past. I encourage you to explore how and under what conditions you write best. As with all writing, the more you do it, the better you'll become.