Bat Boxes are a great way to help out your local bats. They can give bats a place to rest during the day, and some species like to use them as "maternity roosts", in which multiple mothers will raise their pups together!
Bat houses are typically wooden structures, with an entrance in the form of a hole or slot in the bottom. Bat houses may have one or more chambers for bats to cozy into, and can be mounted on the sides of homes, sheds, fences, or posts. (Though bat's prefer it when there's no way other animals could climb up to invade their privacy.)
Bat "condos" are like other bat houses, but bigger! They are typically free-standing structures, and can house hundreds of bats!
Best management practices for bat houses in North America can be found on the U.S Fish and Wildlife Service page. The Alberta Community Bat Program has also published free guidelines for constructing and mounting bat houses.
In addition to all the advantages of keeping bats around, if you have bats roosting somewhere you'd maybe prefer they didn't, providing them a bespoke alternative can be a great option for both parties.
Native Plants
Bats benefit from a healthy ecosystem. That means planting native plants can be a great way to support bats along with many birds and other organisms. In particular, the same flowering plants that are good for pollinators, are in turn, great for bats.
Natural Shelter
Bats can thrive in human-made structures like bat boxes, but they were thriving here long before we started building.
Many species like to live in live trees (nestled in cracks and crevices) or in hollows of dead trees and snags. If you have an old tree on your property, and it's not creating a danger, consider leaving it standing, in case anyone might be calling it home.
Water Sources
Like all of us, bats drink water. Unlike us though, bats typically drink on the wing! Installing ponds, or maintaining existing waterways and wetlands will help keep bats happy and healthy.
Bats are vulnerable to many threats.
Consider limiting pesticide and herbicide use, as bats may be harmed by any toxins in the insects they eat.
Cats are one of the leading causes of mortality for bats (as well as for many other small animals). For those cats that enjoy their time outdoors, it's best for the environment if they are limited to an outdoor enclosure ("catio") or on leash.