I had this sort of trouble when I first bought our shop 5 years ago. The previous owners thought that if they did not set up a net 30 account for every single customer that customer would go somewhere else. The first year was a nightmare trying to get people to pay on time! At the beginning of the following year I sent out email notices with a customer CREDIT application and it had to be filled out and backed with the owner of the companies PERSONAL GUARANTEE. All others can go to the bank if they need financing. I got a grand total of 2 clients that happily filled out the form and sent it back and they pay on time each and every time! Government agencies mostly are set up to bill monthly as well.
I was told that "Nobody will shop with you if you don't charge"....bs...In the end it improved my bottom line as everyone knows, cash flow is king and another really cool thing happened along the process which was this:
By taking a 50% Deposit on EVERY order more than $50.00 we have had no problems with non payment because now the customer is invested.
By Showing our clients that we were indeed serious about our business we became a more respected entity in our community.
As for a intake set up sheet ours is pretty simple. Name, address if necessary, phone number and Job description/instructions.
If you are having a problem with collections I would rethink my "policy" and see if that helps. Many sign shop items are available on the internet and there is no "I'll pay for it later option" there!
Best of luck!