Answer:
picking up trash
encouraging people to vote 
encouraging people to recycle 
conserving water 
Step-by-step explanation:
Being a good citizen would mean different things to different people because humans are essentially uniquely different. 
But, the basic definition of a good citizen is a person who is a resident of a country or place whose actions are beneficial to his country without performing acts that would sabotage the country or make it unsafe, for himself and others. 
Therefore, being a good citizen means that I'll pick up the trash, encourage more people to vote, encourage people to recycle and conserve water.