Your resume is arguable the single most important part of the application process. A well-organized, relevant resume will set you up to get an interview, while a poor resume will get completely lost in the sea of applicants. This is a fairly modern concern, as job postings now get thousands of online applications a day.
When writing the descriptions for the jobs you’ve held, focus on what you accomplished in each position rather than what you did. Listing quantifiable achievements in a numerical manner (increased sales 20%, reduced expenses by 10%, for example) will help your resume stand out.