1. Run a small solar array on my balcony, with recycled lithium batteries for storage. I've made ~100kW of power which I use to basically charge all my devices.
2. Growing Algae two do two things- producing biomass to convert into bio-fuel down the road, and remove carbon from the air.
Rooftop solar & going electric (and destroying your gas car so you're taking it off the road) is the easiest to do, followed by helping others do the same. Off the top of my head, if you own your house see if you can work out a group deal with your neighbors and subsidize their cost. https://ecologi.com and https://www.arcadia.com can give you a feeling of doing something (while actually doing something, even if it's very small.
None of these things really move the needle. If you want to do something, the cold reality of it is some constructive destructive actions need to be taken against the largest polluters- energy companies, major food conglomerates that consume large amounts of plastic, commercial shipping, and others. Pick your poison.
Yoooo. So here's an actual, legit idea I have. A community platform to raise money to donate roof-top solar systems to public schools. Has to be focused, where it's clear the goal and the target area. "We're raising $1,000,000 to fund a solar system in this region. Here are our candidates and our local contract partner." Once that's accomplished, you find a school and get the green light. You work with the contractor to secure an actual cost, and then fundraise for the rest. Then it's installed. Target schools and districts in areas of high coal/dirty power and fund-raise for a full roof-top system for them with some energy storage.
This does two things- allows the schools to spend money elsewhere which helps improve the quality of life in the are (and I'm sure it will be known where the money comes from, but also removes a fairly large consumer of municipal energy.