Politically one huge thing you can do is support investments in pedestrian and bike infrastructure, public transit, and passenger rail, in Maine and across the country. Cars and the infrastructure required to support them are incredibly inefficient and wasteful from both an environmental and financial point of view. I'm not talking about "banning cars" here, but getting to a place where most people don't need a car most of the time because their needs are met by other options. MaineDOT just released a draft of their new Long Range Transportation Plan which I'd encourage you to take a look at, it's pretty cool.

On a similar note, advocate for better land use; ending single family zoning and building denser, mixed use development in your city or town. The closer buildings are together, the less space is required, the less wild land gets destroyed. These days most places have minimum parking requirements and minimum lot sizes for new construction, which adds lots of expense and also results in almost all new buildings taking up a lot more space then they need to, which spreads things out, which makes it hard to walk, which means people have to drive from place to place. Here's a great video going into more detail on that: https://youtu.be/SfsCniN7Nsc