It's actually quite simple. Communicate. After I make the transaction I try my best to stay informed. I email and ask questions regularly at least once a week until the video as filmed and delivered. If there is a delay between payment sent and the scheduled filming date I might wait until a week or two ahead before I start messaging but at some point I start asking questions. I want to know shoot dates or any schedule changes. Performer availability or if changes are necessary. I try not to be bothersome but I paid the money and I at least deserve to be kept informed. I put hundreds sometimes thousands of dollars into a custom order and you better believe I'm going to monitor those investments.
I know most producers are low budget, "do the best they can with what they got" organizations, but I still expect a good product and good service. And in my experience that is what I have encountered. I ask my questions and I get answers. Usually quickly and politely. Sometimes changes have to be made and yes a producer should do their best to inform the customer. But the customer should also try to stay informed.
Basically you put a lot of money into your custom orders. Be sure you put in a lot of attention too. If you don't want to be disappointed with your final product do your diligence and make sure you will be satisfied with your final product by asking questions and making sure want you want is what you are getting.
I also try to get a lot of information, but if a producer tells me something will be filmed on a certain date, I won't bug them till that date unless they come to me.
I think of it more like manageing vendors. They all work differently and are motivated in different ways, so you gotta find what works.
You are statue guy? Do you have an index of your customs?