I'm of the school of thought that:
If you don't trust 'em, don't work for 'em.
Because, believe me, if your client doesn't want to pay you - or can't - no amount of contract language can make them. Not even small claims court. (And I've tried that. But I said "No" to the TV-judge-court, because that's just tacky. Long story.)
Luckily, most people are good people.
Likewise, if your gut or heart tells you that you're not compatible, believe it. (Your head will be screaming, "But we need the money!" Ignore it.) And, rarely, if you get deep into a project and then discover that you and your client have serious trouble understanding each other or have stopped liking or trusting each other, learn how to leave gracefully. One of my earlier bosses, an interior designer, taught me to Fire the Client.
This is not to say that every moment working with a wonderful client will be all celestial harmony and mutual admiration... there might be just a few fleeting moments of, um, disagreement. This is right and natural. Good.
The website BoingBoing today featured the design firm Segura's wonderful new client contract:
You give me money, I’ll give you creative.
I’ll start when the check clears.
Time is money. More time is more money.
I’ll listen to you. You listen to me.
You tell me what you want, I’ll tell you what you need.
You want me to be on time, I want you to be on time.
What you use is yours, what you don’t is mine.
I can’t give you stuff I don’t own.
I’ll try not to be an ass, you should do the same.
If you want something that’s been done before, use that.
PRO BONO
If you want your way, you have to pay.
If you don’t pay, I have final say.
Let’s create something great together.