Most college papers are formal analyses of scholarly subjects---not informal personal responses. Try to make your paper sound as objective as possible. This not only means keeping words like "I" and "you" out of the paper, but also omitting emotion, slang and poetical language. If you are not sure if a word qualifies as slang, look it up in the dictionary to see if it is classified as such. If so, find another expression to convey your message.
Unless otherwise specified by the professor, all college papers have a thesis. A thesis is a statement about the subject at hand that is then supported with evidence throughout the paper. A good college thesis would read something like this:
"Romantic literature differed from neo-classical literature in three distinct ways: its subject matter, its language and its emphasis on novelty over convention."
The rest of the paper would then be divided into three sections, each reinforcing one of the points of the thesis.
To promote unity, the author of a college paper should make sure that each paragraph relates in some way to the thesis. Furthermore, each paragraph should begin with the main idea of the paragraph, followed by examples to reinforce that idea. This gives the reader an instant ability to understand the point of each paragraph from the beginning.
Each subject area has its own style guide that defines formatting details on papers. Style guides often stipulate the size of the margins, size of the font, how to format a title page and how to cite sources. Some disciplines require in-text citation, while others prefer footnotes and/or endnotes. Style guides even have grammatical stipulations---and different style guides have differing rules. For example, the Associated Press style guide does not use a serial comma in a list of three or more items (i.e. eggs, bacon and toast); the Modern Language Association style guide, however, does require use of the serial comma (i.e. eggs, bacon, and toast). Thus, it is important to thumb through the style guide or speak with your professor about the most important aspects of style.