Always choose a cage that is the right size for the bird. Make sure it has enough space to spread its wings, every time it wants to. Do not put a big sized bird in a cage that is too small. That will amount to cruelty. Have to two dedicated bowls in the cage; one for bird feed and the other for water. Birds love to groom themselves and drink water. Always make sure there is clean water available for the birds.
Pay specific attention to the bird feed that you select. Make sure it is of a good quality and suits the bird. If you have two birds living in the same cage, and one of them falls ill, make sure you separate the two to contain the infection.
Female birds may require some privacy while nesting and may feel the need for a shelter, into which they can retire and not be seen by everyone. You may have to make arrangements for such shelters or houses.
These are some very general tips on keeping birds!