Proper use of migrations in a production project

Hello!

I've started working on a CI4 project that is already running for a while now and has a bunch of complex data and db structure but does not uses migrations.

As the documentation itself states: 

You could edit fragments of SQL by hand but you would then be responsible for telling other developers that they need to go and run them. You would also have to keep track of which changes need to be run against the production machines next time you deploy.

And those are exactly the problems we are having!

That being said, I wanted to know how exactly are you supposed to use migrations in production. Should I configure my deploys to run the command "php spark migrate" automatically? Is it safe? What do you recommend as the correct approach and steps to do it correctly and safely?