Bucket sections of the day for internal and external (customer-facing) tasks for the predictable ones.
Find at least an hour or so of focus time to do what's there in the backlog and take the firefighting tasks as they come.
Everything that has to do with company relations with customers and partners has a high priority, then there are agency tasks and after that product (for now).
I brake my day into 3 parts to handle all of my tasks and sometimes move the low priority ones for a later date.
I have to work on this every single day.
There is no single hack, system or method to be honest.
It takes time to figure out what works best for you and this can vary for each project.
Knit API