Check out previous team's essay and executive summary for some ideas. (You can find many on the CD white paper section. MOE's is at
http://www.chiefdelphi.com/media/papers/1983).
We had always written the essay first, then took the highlights to prepare the Executive Summary. A bulletted list is one way to do this - and it saves words. Other teams may do the opposite.
Important - make sure you read the additional information at
http://www.usfirst.org/roboticsprograms/frc/awards
This gives more detailed information as to what is required in the Executive Summary and some hints as to what the judges want to see. If you look at MOE's submission you will see that we took the main points outlined in those instructions and wrote the submission around those.
(I'm sure many teams did this as well, but I can only state what MOE did. Successfully, if I can boast a bit
)