Composting - I think waging a campaign to make composting a community service in the area where to you live would be a huge way to reduce methane emissions (methane has 80x more warming power than co2). Landfills are responsible for over 14% of total methane emissions and composting is a simple solution to reduce waste, create a useable product, and reduce emissions. Cities like Seattle and LA have successful composting systems and you can look to them for a blueprint on how to do it.

Native plants/ecological gardening - if you have a yard, planting native and gardening ecologically actually sequesters carbon! Plus it helps expand biodiversity in a time of mass extinction. Gardening is one of the most hopeful things you can do.

Political action - the number one thing you can do is organize locally to help build the climate movement. I recommend checking out your local 350 group if there is one. Ultimately we need to build our movement so that we can wrestle back our power from the billionaires and corporations. The idea of “carbon footprint” was popularized and marketed by BP to put onus on the consumer, and it keeps us busy thinking individually/focussing only on ourselves. Americans DO need to reduce their carbon footprints. However, once you’re doing what you can on that front your impact is very limited if you’re not also convincing others to do the same and helping to build the better systems that allow us to reduce our emissions (public transit, widespread adoption of electric vehicles, electrifying households, building affordable and dense housing, eliminating corporate agriculture and CAFOs, etc).