Team 20 has used a scouting system for the past few years that has helped us be as successful in competition as possible. We gather data using the scouting sheets below and input the data into an excel document to help with pick lists, match predictions, and strategy.
Ours is one of many systems.
Team #33, the Killer Bees has a history of successful scouting as well: http://killerbees33.com/whitepapers/
Other systems exist, and many work in very different ways than ours.
Hopefully this will help you develop your own scouting system!