My friend and colleague Garrett Dimon wrote about his experiences building and selling a product in his post Hindsight. He gives some advice based on what he learned. You might not agree with everything, but I think his perspective is really interesting and worth checking out. For example, on the balance between building product and doing marketing:

I don’t want to build an operational system to grow a business and then spend no time on the product. I want to design a company to build the product and serve customers. That’s not to say that there shouldn’t be some type of marketing that will need to be done, but I’d rather find ways where marketing is a by-product of the software rather than a separate activity. Checking analytics and numbers eventually becomes relevant for a business, but it’s a spectrum. I want to check the numbers to make sure the business is healthy, but I don’t want to be in a situation where I’m spending days analyzing or optimizing.