Earlier quoted context omitted.
>(payment was 6 months late once) This never gets enough visibility among freelancers / contractors / consultants - it can be really hard to get paid and for smaller amounts of money it often would take too much in legal fees to actually get paid.
Don’t work until payment is made? Offer a discount for early payment? Charge interest on late payments?
This is an important one, as is a clause in your contract that will force them to pay legal fees in the event you have to sue to get them to pay.
>Don’t work until payment is made?
I'm a fan of arrangements where clients pay something up front, then receive work, then pay the rest. No client in their right mind is going to pay the whole amount up front and frankly nor should they. But, if they pay 50% up front, you do work, and then they decide to stiff you for the final payment, you'd better have a good lawyer and a tight contract.