For perspective: I started doing contract CAD work in 1990. I started doing freelance residential and commercial design in 2002. I started practicing architecture in 2007. The tl;dr: If I have doubts about a potential client paying quickly or at all I will validate that doubt by requiring a check rather than just hoping I am wrong.

Typically, I require a substantial retainer to be applied against final invoice. By substantial, I mean big enough to cover all the billings up to payment of the first invoice. Payment terms are always "Due on receipt of invoice." I am not in the no-interest short term unsecured loan business. This means:

1. I will not be upside down where I am owed money for work I have done.

2. I will not discover that the client does not have funds to pay me.

3. I will avoid potential clients with a strong propensity not to pay without investing much time.

4. I will avoid potential clients who will use me as a bank.

5. I will avoid potential clients who believe that since they did not build it, they should not have to pay.

The most significant characteristic of a good client is that they pay quickly and well. Here, "well" can mean a lot or regularly, but preferably both. Writing a check before we start is a good indicator.

There are exceptions of course. Bureaucratic organizations have their payment procedures. On the other hand, if the person who I am talking to cannot authorize a retainer, then I might not be talking to the right decision maker about the financial aspects of the contract.

Good luck.