You will always feel like there is more to do. You could make it a little bit nicer, or prettier, or more user friendly, or more technologically stable. But what you should really focus on is getting your solution to more customers. If your solution is good enough for one customer, it should be good enough for more. You just need to find those people.
You don’t go looking for customers to get money. You should be giving the customer more value than they are paying for. This doesn’t mean that you operate at a loss; it means that you create value beyond what the customer expects for the price they are paying. You find customers because you know that what you have will be valuable to them.
If you could offer diamonds to people who want them, you should. If you have something of value, don’t hold back. There is always more to do, but it isn’t simply finishing your task list. The ‘more-to-do’ is finding the best place to add value and continuing to contribute day-after-day.
There is always more to do for others – go do it.