Include measurable accomplishments such as “increased revenue by 25%” as well as responsibilities. It is easy to get carried away describing your work experience or responsibilities, but keeping it short is crucial. Once you get an interview, you will be expected to go into deeper detail.
It is much easier to update your resume periodically than all at once, so even when you’re employed, set a reminder to refresh your resume every three months, while the information is still fresh in your head. This will make your next job search much easier, should you decide to switch companies or careers in the future.