As a freelance copy editor, I seem to be forever waiting to be paid. I'm out 90 days right now on a project. I'm afraid that if I gripe, I won't get any more work. How can I keep this from happening?
As you well know, a freelancer's lot can be lonely -- and sometimes impoverished. Even though you probably didn't plan to become a bill collector, that's an important part of the job when you're self-employed.
Your best bet is to start out the relationship by clearly stating the terms of payment. You can do this in a letter to the publisher. Ask the publisher to sign a copy of the letter and return it to you. Then, if payment is late, you can mention the letter -- which is a form of contract or agreement. That is not undue griping on your part; you are simply asking for what's legally yours.
Or, you can put the terms of your freelance arrangement in a written contract. Make sure to include deadlines in the contract -- both the date when your work will be finished and the date when you will be paid. If you need help putting your agreement on paper, take a look at Consultant and Independent Contractor Agreements, by Stephen Fishman (Nolo). It includes many sample contracts for a variety of freelance professions.
For more on collecting your bills, see Getting Clients to Pay Up.