Your goal should be to write your resume with both robots and humans in mind. Many organizations use Applicant Tracking Systems to sort and vet resumes, before hiring managers ever take a look at them. This means that you could have the best experience and qualifications in a whole field of candidates, and a pretty decent resume besides, but your information will fall through the cracks if your resume doesn’t contain the right keywords. Good keywords will refer not only to your experience but to the job description in the posting as well.
Once you have written and organized your information according to the type of resume you have chosen, be sure to format it according to typical professional standards. You should use consistent spacing throughout, and evenly sized margins on all sides if possible. It’s generally best to stick to your word processor’s default settings, but in some cases, if you shrink the margins on the left, right, top and bottom, this can help buy more space to fit your resume on one page.