If you did your best to write a complete, clear, and insightful essay within the time allotted, you should have nothing to worry about.
Define a topic: If you`re allowed to choose your own topic, try to pick something that you already know a bit about and that will hold your interest.
On the topic of planning, it`s important to sketch out an idea of how long you want to spend on each section of your essay. If you know the number of paragraphs you`ll need to write ahead of time, you can do this before the exam even starts!
Remember the paragraph-based schedule we discussed above? It`ll be useless if you don`t do regular check-ins during the exam. Keep an eye on the clock to ensure you`re always on track.
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.
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.