edw519, I think your advice is in the right spirit but (as you admit) naïve.
nopassrecover, edw is 100% on target about looking outward. However actors, salons, and teachers are all good examples of people with little money to spend, who would not capture significant extra margins by adding software.
In my estimation, nopassrecover, you would do better to think deeper in the B2B value chain, particularly if you can flex relationships you've made in previous industries you've worked in. Imagine how many more people you could touch writing software that hooks into a shoe factory's shoe machines than making a web store -- and how much less of a customer's attention that would require.
Two consejos that I think are good (but not necessary) for entrepreneurs to follow:
1. Do a part-time job while you work on your own thing.
2. Use knowledge & relationships from businesses you have worked in directly.
And (3) for hackers specifically: spend some time thinking about and researching how the commercial world fits together. Who made the plastic fibres in the salon's brush? How does the aesthetic layout of the salon enable them to charge more? What other construction materials could they have used? What catalogs are thrust in the face of new salon owners and how does that affect the way they see their choices? What's the price history of the real estate they own vis-à-vis the other places they could have set up shop? And more generally: What companies in the world do the most revenue and why? What companies have the most profits?
The salon scheduling example is particularly naïve, because scheduling software would not add much value to either salon owners or customers.
But edw519, I very much agree with you about looking outward (both to meet business minded people and to meet people who don't have iPhones).