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.
Once you hand your exam to the professor, relax! It`s easy to work yourself up after an essay exam when you didn`t get the chance to read your work over or you feel like your arguments were weak.
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.
For example, if you`ve been assigned a five-paragraph expository essay for a high school class, you`ll probably spend the most time on the writing stage; for a college-level argumentative essay, on the other hand, you`ll need to spend more time researching your topic and developing an original argument before you start writing.
Unless if you finished way ahead of schedule, don`t worry about major revisions like reorganizing the structure of the essay–it`s better to hand in an essay with an imperfect structure than a paper that`s impossible to follow because you had to stop halfway through the revision process.
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!