We could all report graffiti, fly posting, etc immediately to the council. It only takes a few minutes to report an issue and they usually clean it up within about 24-48 hours. If we all reported these issues immediately I reckon many of the perpetrators would soon lose interest.

http://www.lovelewisham.org/recycling/fo...spx?item=4

And we could all politely but assertively speak up, and back each other up, as soon as anyone starts playing music out loud on a buses or trains. If you're too afraid to speak up first (which I can understand for some people) then at least try to back up other passengers who they do complain. If lots of passengers all ask the person to switch the music off, at least they will probably feel a bit embarrassed and think twice about doing on their next bus ride.