I may begin by throwing out all without a college degree (even if the job doesn't require one), I then may decide I want someone with current qualifications, and if someone hasn't worked for a year or two, they probably aren't as current as someone with a job doing the same thing every day.
After weeding out a huge chunk, I can then proceed to look at each individually and make my decision. I just don't have the time, or frankly, the need to process each and every one of the 500 resumes I received.