Whoever has been through the ecstasies and agonies of writing the satisfaction is known by an essay(and sometimes the sadness) of finishing. Once you've done all the work of figuring out what you would like to state, coming to an arguable and interesting thesis, analyzing your evidence, organizing your opinions, and contending with counter-arguments, you could feel that you have got nothing left to do but run spell-check, print it out and await your professor's response. But what spell- check can not discern is what readers that are real think or feel if they read your essay: where they could become confused, or annoyed, or bored, or distracted. Anticipating those responses is the working job of an editor—the job you are taking on as you edit your personal work.
While you proceed, keep in mind that sometimes what might seem like a problem that is small mask (be a symptom of) a larger one. A poorly-worded phrase—one that seems, say, unclear or vague—may just need some tweaking to fix; however it may indicate that the thinking has not developed fully yet, you are not quite sure what you would like to state. Your language can be vague or confusing since the basic idea itself is.