Write about what you have learned and know; not what you have done.
Just because you did something in a job doesn’t mean you learned anything. You will get hired for what you know and have learned in your education and previous work or part-time work.
For example: “I was a server in a restaurant for the summer.” Versus – “My summer job as a server in a restaurant helped me develop excellent customer service, teamwork and organizational time-management skills.”
If a potential employer feels comfortable that you have actually learned from your previous jobs and experience they might conclude that they won’t have to teach you these skills.
Remember, when you are right out of school, you represent ‘potential’ to an employer. Tell them you understand and have the skills necessary to be a good hire.