Reading and evaluating student writing is much easier if you know exactly what the professor is asking them to do within a paper. Most professors issue a detailed grading rubric along with the essay's prompt which assists the student in crafting an essay which satisfies the assignment's objectives and is easy to read. If a professor does not include a rubric, ask that she do--it will make the writing process more straightforward for the student and the grading process simpler for you.
Remain fresh, positive and focused by only reading 5 to 10 papers a day. Attempting to tackle a stack of 50 to 60 papers in a few days will quickly lead to exhaustion and errors in grading. Begin grading as soon as you receive the essays to provide you with enough time to distribute your workload over a few days or a week.
Many grading assistants find it helpful to establish some kind of order or method while working. This may include arranging the papers in alphabetical order or covering the student names (if you know people or have friends in the class) to avoid any lingering bias. Find a habit that allows you to work most efficiently and stick to it for quick and consistent grading.
It is impossible to be an effective grader while working in a loud environment with many distractions. A noisy apartment, crowded kitchen or during a party at your friend's place are examples of poor places to grade. Seek out quiet, isolated places like the top floor of the library or a closed room late at night. Tranquil locations will help you stay focused, determined and engaged.
No student likes a brash, unfriendly grader. In your response comments and feedback, reinforce the student's attempts and encourage him in his writing. Adopt a humorous, light tone in any long responses and always explain what was good and effective about the paper before describing what needs attention or rewriting. If the professor allows it, offer to meet with students to discuss their work.