[mattbgates]

I've always worked this way: I'll do the work for you because you need it. I send you an invoice. You pay. I have a client who gets busy and I sometimes I have to remind her to pay me. Usually, she'll need more work done, and that's when I remind her that until she pays her invoice, no more work will be done. She has always paid it. Because to turn to anyone else will require finding someone who actually knows what they are doing.

If you have any thing running in which they rely on you, suspend it in order to get their attention until payment is due. If a large bill is due, and they are having trouble paying it, than offer them to pay X by this date, and another X by this date. If no payment is made to you, than inform them that if they don't pay X by a certain date, they will be terminated and any future work for them will not be considered at all.

If you wish, you can throw in some legal jargon in there that you will be getting a lawyer or proceeding to small claims court, if you wish to take it that far.