I often teach my students to write by encouraging them to use a simple, four-step process which I abbreviate as "SIEL." Here are the four steps:
S: State your argument
I: Illustrate your argument with a quotation.
E: Explain in some detail how your quotation does indeed illustrate your argument.
L: Link to the next argument.
In a single paragraph making a single argument, you would not need the link, or L.
Here is an example of this pattern as used in an essay about a poem by William Blake:
[STATE:] Clearly this work exemplifies many of Blake’s most prominent themes. [ILLUSTRATE:] For instance, his standard emphasis on the beauty of nature appears when he describes how the chimney sweepers, when they are freed mentally (from their woes), "down a green plain, leaping, laughing . . . run / and wash in a river and shine in the sun" (15‑16). [EXPLAIN:] These lines illustrate Blake'sfrequent emphasis on the beauties of nature by depicting innocent children in an appealing natural landscape. Natural beauty is emphasized through the positive references to the plain, the river, and the sun. These references imply earth, water, and fire, three of the four traditional elements of nature (air being the fourth). The children themselves also seem naturally beautiful since they "shine." Human beauty here becomes part of natural beauty. [LINK:] However,[STATE:] a second major theme of Blake’s verse is a stress on personal and social freedom.
I can easily imagine you using this pattern to write a 12-sentence paragraph about The Great Gatsby. For example, you could make an argument such as the following:
S: Often single sentences in The Great Gatsby illustrate many of the novel's major themes and techniques.
I: One such sentence, for example, is the following: QUOTE A REPRESENTATIVE SENTENCE HERE, SUCH AS THE FIRST OR LAST SENTENCE OF THE BOOK OR THE FIRST OR LAST SENTENCE OF A PARTICULAR CHAPTER.
E: EXPLAIN, IN DETAIL, HOW THAT SENTENCE IS A TYPICAL OR REPRESENTATIVE SENTENCE FROM THIS NOVEL. FOR EXAMPLE, HOW IS IT TYPICAL IN THE IMAGERY IT USES? HOW IS IT TYPICAL IN ITS TONE? HOW IS IT TYPICAL IN THE WAY IN CONTRIBUTES TO CHARACTERIZATION OR ATMOSPHERE OR THEMATIC DEVELOPMENT?
Here, for instance, is the very last sentence of the novel: "So we beat on, boats against the current, borne back ceaselessly into the past."
You might ask yourself how this sentence is typical of the book in its themes (such as the past), in its sounds (such as in its almost musical use of alliteration), and in its imagery (such as in its references to boats).
I think you'll find, if you use the SIEL method, what many of my own students have found: that it makes the writing of papers much easier and much less puzzling or mysterious than the process might otherwise seem. Using the SIEL method can help you order your thoughts logically and can help give you a very good idea of what you should do next.