The top of your resume is prime real estate. If you want an employer to read through your resume, you've got to catch their attention immediately.
Think of the top portion as an umbrella, where you summarize all of your most important features...not necessarily what you think of as your best features, but those the type of employer you are targeting will care about.
Here are some ideas to get you started.
1. Identify recognizable names from your work history (organizations, people, events, etc.)
2. List industries you've worked in and/or roles you've held
3. Include major titles and/or honors/awards
It doesn't take long for an employer to pass on a resume these days. Make sure you're not passed over by highlighting the things they will understand and care about.