I write a proposal, have it signed, and I require a 50% deposit prior to starting any job. I read in TCI that you should do this, and it has saved my butt a couple of times. I have been burned in the past before I started having proposals signed.
I have never had a problem with the proposals. In fact, customers seem happy to do it. As if they respect you a little more. And the cash flow is a lot better. If the job goes a couple of extra days, due to weather or who knows what, well at least you've got 1/2 the bills in the bank.
Tree work usually costs a pretty penny. We use some of the coolest tools out there, and they're not cheap! Most of us have some serious $ tied up in this business. Chip truck, chipper, saws, ropes, saddles, spikes, stump grinders, etc. Not to mention that our work is inherently dangerous. So, our service is expensive. When someone buys anything from Sears for over $1K (and usually less than that), you better bet they'll be signing some contracts.
Now, my 1/2 down policy doesn't seem to work so well with contractors. But you no what? They've been the biggest pain in the rump for me since I can remember! I do fine with strictly residential. So, unless someone can tell me why I should put out a $1000 to rent equip., pay employees, gas, oil, and the works...and then wait a month to get any money, I'll stick with my current plan. Speaking of which, I plan to start a thread soon about contractors!
I'll have to agree 100% though...if a customer is the slightest bit slimy, lose 'em. You're just asking for a conflict, you'll probably lose them anyway, and then they'll be telling rumors about you.
Sorry about getting on the soapbox but y'all struck a chord here.