Every community has different concerns. With this in mind, here is a list of possible topics you could address:
1) Littering/trash in public places 2) Funding for education 3) Safety issues (need for more police, better street lights, potholes on roads, etc).
Here are some ways you can effectively communicate with government officials:
1) Send a letter to their office. 2) Try to set up an interview with the person to express your concern. 3) Call your representative to voice your concern with their office.
You could use statistics, news stories, or pictures of the problem in order to convince people to join your cause. Creating a petition, organizing a rally, or protesting peacefully are all ways you can help invoke change.
My community has traffic in every corner of the street. I can effectively communicate this issue to the government by starting a petition and getting every person in the community to sign. Then, we can mail it to a government official once we have everyone's signature. To convince people to sign, I will post statistics online of congestion over the past month and place papers on trees and walls around the community to show how big of a problem it is.