Make the paragraph the unit of composition. Each main point in your essay deserves its own paragraph, and each paragraph must have one clear main point. Each paragraph must add something new and significant to the establishment of the thesis. The relation of each paragraph to what precedes it or to the whole should be clear. Paragraphs must be composed entirely of complete sentences, each of which contributes to the main point of the paragraph.
Concision promotes clarity.
Always state your points as concisely as you can without sacrificing necessary information. Concision almost invariably makes writing more clear, because it demands that you keep your priorities straight at all times, even within each sentence. Use statements, not questions. Questions are seldom appropriate in an essay. In general, questions add little to an essay, because arguments and explanations must be composed of declarative statements.