On matters like public transportation, how can I influence the public opinion and politicians' opinions. For the public I was thinking to get them to sign petitions, or even talking to the media, but thats all I can think of.
If you have an issue that is important to you, the first step is to find out who is already involved in that issue. There is no need to reinvent the wheel, and you will do better joining a well-run organization than starting your own, at least in the beginning. If there are no influential organizations in your issue, then find an organization with common or similar interests and branch off from there.
Write letters, be informed on the issues, and call frequently. Believe it or not, a very small number, relatively, do any of those things. By participating consistently and in a responsible manner, you automatically make yourself more influential than the vast majority of Americans.
If you call long enough, and your questions and comments show how informed and rational you are, then you are more likely to get to talk to aides and advisers to congressmen that specialize in your topic field of policy. Then you're in the ball game.
There are many ways to influence public opinion and politicians. Your suggestion of creating a petition is a good one. Other ways could include writing, telephoning or emailing your elected officials. Believe it or not, politicians do listen to and respond to their constituents. Writing a letter to an editor of a local or regional paper is another way to get your opinion out to the public. Another way to influence politicians and the public to is to start a blog. There are many free blog sites on the internet today. Calling nationally syndicated radio programs will allow many millions of people to hear your opinion. Joining an organization that is concerned with the issues you find important can really influence the public and politicians. For instance, if you are concerned about environmental issues, you may want to join Greenpeace. There is power in numbers. And don’t forget to vote. Voting in favor of politicians who reflect your ideals can influence issues. Voting for or against local and state propositions and ballot measures is also important.