Spend as much time on understanding the marketing and sales of your business early on. Marketing can generate demand, but you also have to be able to close the business that comes through the door. That can be investors, customers, or employees. Whatever it is, as a founder, you are selling your ideas, solutions, and vision. The reason why it is really important to get good at that it's just something that you have to do is you gotta get comfortable with being uncomfortable. Sales is usually uncomfortable for a lot of people.