Being a copywriter can have its advantages, but you can also feel that you just wish with all of your heart, that you'd stayed in your cosy 9-5 with a guaranteed pay-cheque at the end of every month.
Many copywriters charge a 50% upfront fee, in fact if you ask in any group of pro copywriters who doesn't, the show of hands would be stark.
Sometimes though, you just have to take that risk and work in good faith.
In that situation, waiting for payment can feel ... nerve-wracking.
What happens if they decide to not pay you? After all, they have your work that you've spent hours over, and while it would be illegal, there is nothing stopping them from using it.
Taking them to court can be an enormous faff and an incredible waste of time. And that's if you win. The whole process can take months.
There are some fairly lame procedures that give you rights to demand it be taken down, but that still doesn't get you payment for the effort you've put in, nor does it satisfy the need for a wrong to be righted.
Of course, there are tactics that can be used to apply pressure, but they kind of depend on where you're comfortable - I've known a freelancer threaten to go straight to a client (when working for an agency) and ask for payment. He got his money.
Personally, I think keeping it ethical is the way to go, and if it goes belly-up, then you've learnt something.
Understanding your rights is the very first course of action.
If you have a payment deadline set, then good, but if nothing was agreed beforehand, you have to wait between 30 - 60 days before taking action (depending on company).
I find that a 'strong' letter usually helps get the ball rolling, or the wallets opening (I can supply a letter if needed), but sometimes you can rub the client the wrong way.
Only you know how your client is likely to react.