7. Plant a tree. Shade, serenity, sustainability—trees add so much to the urban landscape and ask so little. Many cities give away free trees, have planting services, or require tree planting permits, so check your local rules before you start digging.
I will add, you are almost always free to plant on your own property, but in town it is advisable to identify any buried infrastructure first. Rural areas have most of that stuff along the roads, so it's easier to learn the few bits of your property to avoid digging in. Most locales have a number/email where you can ask someone to come flag all the stuff so you don't hit it.