Before you start working on your topic or your specific interactions with the reader, make sure you understand the requirements for your essay. It might amaze you how many essays fail to follow simple directions. These directions normally come from your reader. Your reader will like you and have more patience with you if you follow the directions, not if you don't.
The directions include everything from the recommended number of pages or words to the manner, place, and time at which you should submit your essay.
Moreover, if you have been given a "prompt" or a specific essay topic, do not write about something else. Note that readers search for plagiarism more vigorously when they notice that an essay does not really answer the question or follow the prompt.
Remember that an essay is an action. A prompt often gives you a specific activity to complete. Look for the key verb in the prompt. If you do not know what the verb means, numerous web sites provide insight about how to interpret verbs such as analyze, comment, compare, define, describe, discuss, explain, identify, list, prove, summarize, and so on.
Note that if there is no prompt, you can use one of these key verbs to launch your essay. Can you think of something beautiful worth commenting on, something difficult or unusual that is worth explaining, something complicated that you should summarize, etc.?