Here's how I keep my AR as low as possible.
1) I tell people when I quote a job that I don't bill for any job less than $1000. We letter vehicles for a very large construction company. They don't squabble over prices but would typically take 60-90 days to pay. When I told my contact our terms had changed to no billing below $1000, he never missed a beat, and gave me their corporate credit card.
2) Standard terms are 50% deposit with balance at installation. Remember, these are custom things we're making. Try to find a company who will make you something custom and bill you for it. I very nicely tell my clients that our pricing is based on them funding their project, not us.
Occasionally we will accept a project that we can't get a deposit for or get payed the balance at completion but not often. When we do find ourselves in that position, we include extra in the job for providing funding.
I once told a client that I'd made a pact with the bank "I wouldn't give out loans if they wouldn't make signs" he got a good laugh and we got the deposit.