Spell check. Whatever you do--make sure there are no typos, spelling errors, or obvious grammatical errors.
Decide what type of position you are applying for and tailor your resume for that type of position--that is, highlight skills in your previous jobs that will be beneficial to this position and put the types of skills you possess and will need for this position at the top of your skills list.
Make sure the resume is laid out neatly, spaced consistently, and is clean--enough white space so it isn't overcrowded.
Try to keep it on the shorter side by using concise sentences and by not including extraneous information.
Depending on where your life, think about which areas you want to put first--for example, if you graduated from college/high school 10 years ago and have been working consistently since, put education at the end of your resume because work experience is more relevant and recent. If you just graduated, put your school information before work experience unless you've been working steadily in your field since you've been in school.