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.
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.