Have a clear, list of features that you think you need to bring a product to market.
Plan out all UI/UX elements and have a very specific sitemap and procedure map.
"Feature creep" becomes a huge issue since the "business guy" doesn't understand the technical challenges.
Many times, the programmer is someone with less experience who is willing to take a chance and doesn't have the knowledge to create a flexible and scalable architecture.
For most of them you will be a significant client and will receive the 5start treatment.
Their founders being entrepreneurs themselves will understand the way you think.
In fact, when you see a "free support" promise, this is a big red flag -- a clear attempt to make a sale without regard to tomorrow.
I've identified a few niche dating sites that I know could turn a profit, however I lack the programming experience to write a custom CMS.
We for example have a lot of experience rolling out the minimum viable portion of the product and testing, which we have done with other start ups.
Wireframes, UX/UI, design - a company has seen many projects and from many different angles and will give you expertise for free as long as they are developing your product.
I have enough experience from prior projects to know how to outcompete most other sites.
If you don't currently have the skills yourself, you generally have two options: pay someone; or learn programming. In my experience, most people asking this question are looking for a programmer to "partner up with" where the programmer puts in all of the up-front time investment and the marketing guy helps monetize the idea.