I'm going to start with a list of ways, easiest to hardest (about) that you can help save the planet. Some of these might only apply to Americas but the concepts are still the same.
1) Go see the new Disney film "Earth" which is out in theaters today. Disney has promised to plant a tree for every customer who goes to see this film opening weekend. So you have until the last showing on Sunday (April 26) to see this movie. Although the trailer made the movie out to be stock footage of animals I assure you almost all of those scenes were used in the trailer and there's still 6 reels of stunning visuals to behold. Much of it has been shot specifically for the movie. Go see it.
2) Donate $10 (I think) to the Arbor Day Foundation. Doing this not only supports the planting of tree but they'll also send you 10 saplings in the mail. When given the choice, you should always go with trees native to your region. This way insects will find the most use from them and this in turn benefits migratory birds and so on. The only real issue I recall having with this place is they don't monitor what varieties of the tree they give out. So if you keep the Dogwood saplings for example they might be our native Cornus florida, or the imported Cornus kousa which is useless to insects of North America. However, it's better to plant a tree than to not as it will reduce your carbon footprint. Most of the tree they give out are beautiful and beneficial.
3) Plant a garden. Anything that reduces the size of your lawn is greatly beneficial as lawn mowers use way more gas than cars do. Fruits and Vegetables, regardless of their origin benefit you because you're getting some much needed vitamins in your diet. Plan for the future and plant a fruit tree and grape vine. Though you probably won't get a lot of fruit off of either for the first few years, compare the cost of the fruit to the cost of the tree. Varieties of Sunflowers will benefit pollinators and you'll start to see Gold Finches and maybe other birds as well. There are loads of options out there so start taking advantage of them. Concord Grapes, Vitis labrusca, is native to the America, and very disease resistant. Blueberries, Cranberries, and Huckleberries are also native and do well here. Blueberry bushes can be planted right in the landscape though do require some acidity and good drainage in the soil.
Well those are my three for the day.