When a database is in a production environment and updates needs to be made (new/updated tables, new database objects, etc.) what steps do you think

When a database is in a production environment and updates needs to be made (new/updated tables, new database objects, etc.) what steps do you think are needed to make these changes? Keep in mind that a database has applications and users that use it.  Write your outline of steps you need to perform and also what precautionary measures need to be taken.