I think that first you would have to know the topic you need to write about, then Create an outline for (What you will put in each paragraph), Have all of your facts looked up, prepared and on a scrap peice of paper. Write the essay on paper, proof read, fix errors, rewrite, and Type ( If you have to or want to).
I'm not actually sure, however, this is how I make essays and I hope this helps ^-^
Taking an idea and rephrasing it so as to use the content of the idea but not the exact wording
Answer:
at an angle of 90° to a given line, plane, or surface
