Sometimes called "higher" and "lower" concerns, it's important to prioritize major issues like content, creative thinking, and organization over more minor issues like grammar, usage, and spelling. These designations obviously depend upon many things, like the assignment, the grade-level of your students, and their individual concerns. If you're in the middle of a unit on comma usage, it's perfectly fine to call that a "higher" concern. But in general, a basic writing assignment should prioritize the higher concerns listed above. When you've got a stack of 50 or 100 papers to go through and another stack of quizzes to finish and lessons to plan it can be tempting to jump right in and start slapping Bs on everything. Resist that temptation. Read through each essay individually before marking anything. Look for the highest order of concerns first:  Does the student address the prompt and fulfill the assignment effectively? Does the student think creatively? Does the student clearly state their argument, or thesis? Is the thesis developed over the course of the assignment? Does the writer provide evidence? Does the paper show evidence of organization and revision, or does it seem like a first draft? Getting an assignment back that looks like someone bled all over it can be a source of great anxiety in the life of a student. Some teachers argue that red asserts authority. While that may be true, there are other ways to assert your authority than pen color. Marking essays in pencil can suggest that the issues are easily fixable, keeping the student looking forward, rather than dwelling on their success or failure. Pencil, blue, or black pen is perfectly appropriate. Write comments, criticisms, and questions in the margins as neatly as possible. Find moments that the writer needs to clarify and circle them or underline them. Be as specific as possible when asking questions. "What?" is not a particularly helpful question to scrawl in the margin, compared to "What do you mean by 'some societies'?" When you've addressed the most important issues of the essay, its content, feel free to mark some lower-order concerns, like usage, grammar, and punctuation. Depending on the grade-level of the essays and the skill-level of your students, these may be more or less important. Typical proofreading marks include the following:  ¶ = to start a new paragraph three underscores under a letter = to lowercase or uppercase the letter "sp" = word is spelled incorrectly word crossed out with a small "pigtail" above = word needs to be deleted Some teachers use the first page as a rule of thumb for marking later concerns. If there are sentence-level issues, mark them on the first page and then stop marking them throughout the essay, especially if the assignment needs more revision.
Learn the difference between major and minor errors. Read the paper through once without marking anything. Keep the red pen in your desk. Read through the paper again with your pencil ready. Proofread for usage and other lower-order concerns.