At the city level, it is shockingly easy to have a voice, and an impact. It may not seem that way to someone not currently involved in local city politics or policies, but that is usually a misimpression.
One of the easiest methods is to find a city web page and discover who is in charge of issues that are important to you, and email away. In addition to department heads, Mayors, City Council members, and City Managers should all be on your one-person email campaign list.
Some things to consider emailing about:
1. Walkable, livable cities (requires special attention at the Planning and Transportation departments for creating a human scale environment);
2. Green building requirements, such as LEED certification or mandatory solar, for new construction;
3. Municipal Utility policies: Renewables mix, solar incentives, more.
4. City operational concerns, ranging from efficient use of natural resources to reducing emissions from city equipment like buses or skiploaders.
In the City of Pasadena, there are also a number of commissions -- staffed by citizen volunteers, not politicians -- to which you can take your ideas and concerns.
These quasi-insiders can often translate your issue into terms that the local government can work with effectively. They can also become a champion of your issue, and came at the issue from the inside, at the same time you work on the outside.
Some recent examples: The City of Pasadena recently became signatory to a UN document setting goals for combating global warming; and after citizen input the City dropped efforts to extend coal generation contracts for the local electric utility. ("No new coal" is now the official city policy(!).)
Bring your city around on key issues, and help yourself -- and thousands of your neighbors -- to an easy, Green future!