Grading essay questions is in large part a subjective process. Sloppy, difficult to read handwriting might actually lower your grade. Avoid filler and sentences that say nothing. Write as if you expect the person grading your test to be tired, bored and overworked. Use a pen.
Ink is easier to read than pencil.
Write on one side of the paper. Writing on the back page will show through and may make it harder to read. Examine two or more things. Identify similarities and differences. Set in opposition.