What do first-time founders get wrong most often?

They build for too long before selling anything, and they compete on price because it is the only lever that needs no thought. Both come from avoiding the conversation with a customer.

Why the answer is what it is

The third, less discussed: they measure revenue rather than contribution, so a growing store can be quietly getting worse for a year. Every one of these is fixed by talking to buyers earlier than is comfortable.

What this looks like in practice

The best ideas usually come from a job somebody already had. You notice a problem because you lived inside it, not because you brainstormed.

A market that already spends money is easier than a market you have to convince exists. Competition is evidence, not a warning.

Test whether people will pay before building anything. A hundred people saying they like it is worth less than one paying.

Where a mobile app comes into it

If the idea is a shop, the sequence matters: sell first, prove people come back, then build the app. An app before the customers is a cost with nothing to do.