Voting is a thing you should do.

It's about the only time you can have a direct say and add to the consensus.

Some years I'll vote third party. Other years I'm basically voting for "not THAT guy, the other guy"

Think of it like running a node to strengthen the network. You can't single-handedly enforce the network rules, but you add to the strength of the consensus mechanism. 

It requires minimal effort to participate this way every couple of years.

The other thing you should do from time to time is write to your elected officials.