What do you need to do before writing? First of all, it requires proper planning. Take no more than 2-3 minutes to outline your essay, paying specific attention to planning not only specific examples to support each argument you have, but the academic wording for each idea. With planning, you will be able to begin with whatever part of the essay is easiest for you, without having to struggle over the introduction, for example, if you know this part is particularly hard for you. Also, as it is often given in AP Computer Science homework help pages, decide how many paragraphs you want to include and what argument each paragraph will describe.