Take note of the amount of time allotted for the exam and split it into reasonably-sized segments, leaving some time at the end for revision if possible. Without a schedule to follow, it`s easy to become too focused on a single paragraph and run out of time to finish the essay.
Understand your assignment: What is the goal of this essay? What is the length and deadline of the assignment? Is there anything you need to clarify with your teacher or professor?
For this reason, it can be helpful to simulate the conditions of a timed exam before the actual day: pick a practice question, find some lined paper, set a stopwatch, and see how you do!
However, this thinking process does not reflect the reality of the situation. In fact, even if your teacher hasn`t given you any hints about the essay question, you do know what it will be about: the concepts and ideas you`ve discussed in the course.
Do your research: Read primary and secondary sources and take notes to help you work out your position and angle on the topic. You`ll use these as evidence for your points.
If you have enough time left over, read your essay again and make corrections. When you`re working under time pressure, it`s easy to make grammar mistakes or produce hard-to-follow sentences; the final few minutes are your chance to clean up those errors.