I love games, including designing rules. My rules, games and other creations tend to be overly complicated or at least sophisticated, so take my following experience share with a grain of salt, please.
1. Rewards work better than punishments. Players love rewards. People love rewards. Make your rewards valueable to others, and you can indirectly lead those others behavior by offering these rewards for the behavior you want to see.
I may not be sure if providing a +10...