Part of this is in the way you present - do you have a business structure, do you use all the right terminology and language? I personally say I am a small busi

Part of this is in the way you present - do you have a business structure, do you use all the right terminology and language? I personally say I am a small business and rely on the funds coming in, and cannot afford to loan money to a large business then get into a position where a large amount of money is outstanding. The payment terms are part of my negotiation before I sign the contract, and go on the contract. This includes politely informing that I stop work if the owed balance gets to the size I specify, typically two weeks fulltime. Having got agreement at the executive level, it often gets tried on anyway, but the very first day it's late I start letting people know, and consuming their time, and reiterating reasons why its setup to pay. I follow the chain of people to get actual contact to the accounts paying person and build a personal relationship with them, as an individual they have a commitment to paying rather than just another bill on the stack. An individual who will ring them for a person plea, plus consume their time, if they don't pay as agreed. This reminds them it's an issue and that my work continuing relies on them paying, as they agreed. I do this politely, but clearly, and conscientiously. I find this significantly increases my chances of getting paid properly. The critical time for this is when the first, and perhaps second bills are paid. Once they are trained that yours is a bill to to pay without games, it tends to become smooth sailing. Also, in the case where it is delayed - stop working. This is critical. If you work when they are not paying as agreed you're undermining your main leverage and will possibly have big problems. Be polite, always, yet clear and firm about the agreements made, and be ready to walk away and find new work if necessary. Usually late payments will be resolved in days to a week and if it's taking longer then put your effort to finding new work.