Some advice that gets passed around and is useful - understand the database schema. For a good number of applications, if you can understand the database schema

Some advice that gets passed around and is useful - understand the database schema. For a good number of applications, if you can understand the database schema you can guess at a lot of the functionality and a lot of the code base will just be taking data back and forth from a database to either a UI or an API endpoint. This doesn't work for all applications, but a good number.