Refer to the specific mathematical laws that you employed to arrive at your solution to the question. Referring to these laws frequently demonstrates that you grasp the question and are fully aware of the laws of calculus.
Show all of your work. Write down each step you take to arrive at the solution to enhance your score. The graders are most concerned with the method you use to solve a problem, not necessarily that the answer is correct. An incorrect solution with the proper steps is always better than the correct solution with no evidence.
Write down the equations and mathematical functions that you input into your calculator.