Caring for your new bird always begins with buying the right cage. Since birds fly sideways, not up and down, a cage should be at least as wide as it is tall.
Exceptions to this rule are canaries and finches, both of whom do fine with tall cages. Aluminum wire cages are the most expensive, but they're the easiest to clean. Antique cages are beautiful and decorative, but may have lead-based paint on them which is poisonous to an inquisitively nibbling bird.
You'll need something to line the bottom of the bird cage. The best and cheapest thing is paper towels or plain old newspaper; you can change it every day without a lot of expense. At night you'll probably want a cover for the cage so the bird will settle down. This also keeps it a bit warmer.
Since birds get their exercise flying from one branch to another, a bird should have several perches in its cage. These can simply be tree branches or can be perches made for this purpose. Make sure there are some on each side of the cage to promote exercise. You'll want to wash them every week when you do a thorough cage cleaning, and if they become really grubby or worn, you'll want to replace them. Every cage bird needs a cuttlebone to trim its beak on. Fasten one into the cage with the rough side inward toward the bird and watch its enjoyment!
A Balanced Diet
The simplest, though not necessarily the best, food for your bird is a seed mix. Buy the recommended one for your bird from the pet store bulk bin, since that tends to be fresher. The danger here lies in the fact that some birds will pick one or two kinds of seed out of the mix, leave the others, and cause themselves to have poor nutrition. Some avian vets suggest pelleted food as well, some fruit,such as a bit of banana or apple, and greens. Greens can be things like leaf lettuce, kale, and even unsprayed dandelion leaves from your yard. As a treat you can give your bird a little yogurt, toast, or cooked egg off your hand. Make sure there is always fresh water available.
Your bird's best entertainment, as a rule, is your company or the company of another bird. Since you won't be entertaining your bird all day long, toys are in order. Birds have individual tastes in toys, though, and you may have to buy a few before finding the right ones for your particular bird. Mirrors fastened to a cage wall beside a perch are a favorite.
Most birds love baths in a shallow bowl set on the cage floor. Occasionally a bird may prefer being carefully held and showered under the faucet, but this must be done carefully. If your bird won't bathe at all, try misting it with warm water a few times a week to encourage it to groom itself.
After you bring your bird home from the pet store or breeder, take it to a vet, preferably an avian vet, for an exam. This should be repeated every year or if the bird seems sick. Sprays of any kind, even perfume, can harm your pet, so close the door to your bird's room before you use them! Be prepared for the bird to be stressed and a bit droopy for the first few days. Your bird friend has been through a major change, but in a few days it should love its new life with you!