What I do is small but over time I've made some impacts...

1) Find out if there is a government body that deals with bicycle and/or pedestrian issues. These are typically called BAC or BPAC (Bicycle Pedestrian Advisory Comittee). I am a member of the Broward County BAC. A lot of this is blowing off steam but on occasion I get to point out problem areas and sometimes the state and county fix them! Also showing interest is something the road (state/county/city) like to see. You are a cyclist and can explain to them why a design is a problem for you. Sometimes they don't see it because they are not all cyclist.

2) When possible volunteer to do civic bicycle stuff like kid bicycle rodeos. They are a drag on your riding time but if you can at least do one a year then you will make lots of good contacts with county/city officials and also probably law enforcement officers esp bicycle officers.

3) Try to set up a promotion for bicycle week. For us here in South Florida the month of May is too hot so we are working on doing it during March.

4) Join a bicycle club and try to motivate them to help with the above causes.

5) Never let the above get in the way of your personal cycling goals