I totally get this, and sure others do as well. Personally, this may sound a bit harsh to some, and for some business minded people but here it goes. I don't haggle with my prices, and I'm not going to chase anyone around for payment. Whenever a person comes my way for my services the first thing is presenting a standard contract for the most part. Contracts has not much to do with trust, but rather contracts helps everyone fulfill their obligations as all keeps in mind what is requested. What is expected and how services will be delivered, as well as, payment form. Most people are not in business to make friends, but we are in business to make money and not lose any if we can help it. I have signed contracts with family members, including my own mom and dad. It's not personal as a matter of fact a contract usually helps all parties involved to stay in the business mindframe. A man word is his bond, is hard to come by these days. In my contract I provide at least three options on how to pay for my services. Along with expected dates. Also is placed within the document what happens should I, or my prospective patron do not, or cannot keep to the contract. I also suggest working with BBB whenever someone just refuses to pay you, as they are very good with resolve. 

But in regards to getting people to pay me as they should and on a timely basis I nip it in the bud from the start via contracts. If a person doesn't want to sign a contract with me then I don't want to do any business with them.

And, if after sending 30, 60 to 90 days collection notice and have not received all monies, or not received a return call I will proceed with collections. It's not personal. It's business. 

Good luck!