Successfully gardening for wildlife means providing all the essentials of food and water, and perhaps shelter, depending upon available space and the wildlife you mean to encourage. It is also important to what wildlife lives in your area, as it will do little good to build a regulation birdhouse for bluebirds if they do not range as far as your state. The National Wildlife Federation is one place to learn about wildlife needs before starting your wildlife garden.
Put in a large pond if space permits. If your yard is tiny or you do not want to maintain a large body of water, consider shallow pools or birdbaths where birds can drink and bathe. Set shallow trays or terra cotta plant saucers on stumps, tall flat-topped rocks or other elevated surfaces. A large stone placed in the trays give butterflies and other insects something to rest on, so they can use them too. Consider a recirculating stream or small pool for frogs, lizards, turtles and other "grounded" animals to drink as well. Include rocks or logs in the water and anchored to the bank for small animals to climb out if they accidentally fall in the pool.
Grow the food wildlife likes and leave it to them to bring in the harvest. It will be fresher and more nutritious and save you money by not purchasing food for the animals. Grow millet, sunflowers, thistle, amaranth, blackberries and other seed- or fruit-bearing plants for birds. Plant wildflowers like bee balm, native coneflowers, milkweeds, black-eyed Susans or other daisy-like plants, and herbs, especially thyme, lavender, lemon balm and rosemary, for bees and butterflies. If you have room, acorn-bearing oaks or nut trees like hickory, pecan or walnut will bring in squirrels and chipmunks. Include members of the cabbage family, clover, dandelions and a variety of grasses for the rabbits and other herbivores.
Birds will appreciate brush piles for nighttime roosting, and small mammals, reptiles and amphibians will use them too. An overturned flowerpot with a hole along the rim for a doorway makes a shelter for toads on a hot day, and a south facing dry, stacked-stone wall provides sleeping nooks and crannies for small lizards and geckos, while the top gives them a place to warm up in the sun. Grow ivy or other climbing vines on fences, trees or sides of outbuildings to provide private nesting spaces for small birds. Include low shrubs in your plantings for low nesters like buntings.
Build bee, butterfly and bat houses along with birdhouses and nesting shelves. Follow recommendations from reputable wildlife organizations such as National Audubon Society or the U.S. Fish and Wildlife Service for individual species' needs, especially entry holes sizes and cavity depths for bird and bat houses, to ensure maximum success.
Make a feeding table in a sheltered area of your garden--an old picnic table with a cookie sheet or other shallow tray on top will do--and load it with a variety of seeds, fruits and insect treats to attract many kinds of birds as well as squirrels. Squirrels love whole, dried corn and peanuts, while many birds eat oranges, apples, mealworms and crickets as well as seed.