Make sure no other pets have access to the bird or bird cage: especially cats, dogs, ferrets.
These are predators.
Birds are prey animals.
Make sure all doors and windows are closed.
Windows and mirrors should be covered to prevent birds from flying into them.
Toxic substances should not be available for curious birds to chew or injest: alcohol, caffeine, chocolate, avocado, etc.
Teflon (found in non-stick surfaces like cookware, hair dryers, portable space heaters), candles, perfumes, incense, paint, nail polish, febreeze and other air fresheners, and harsh cleaners should not be used anywhere near your birds as they are toxic and the fumes from these can cause death.
Avoid loose bedding as it can cause crop impaction and easily grows deadly mold.
Sand perches cause bumblefoot and other foot sores.
Mite protectors harsh fumes are toxic for birds.