Might sound silly as when you set your invoice terms (Usually 30 days) then the client or production company should pay you on time, but this doesn’t happen 100% of the time for me. So there are a few things you can do as gentle reminders to help maintain your cashflow and all the adult things like rent and bills.
Here are a few pointers to try:
Put your invoice terms less than 30 days
This means you can get a reminder on your end that the invoice is nearly due and enquire to the accounts department that the invoice is still on schedule to be paid. If it is unlikely to be paid on time at least you know before hand.
I wouldn’t do this will every client all the time but if its important like when cash is slow or work is slow then it is a good tactic later on.