The mental model I’ve developed across a few products — from first customer to first profitable month.
Start smaller than you want
Most people start building products the way they were taught to write essays: outline first, research thoroughly, and only then begin. In practice the opposite works better. Start with a small, slightly uncomfortable version of the thing and learn from the gap between what you imagined and what actually happened.
Ten customers teach you everything
Every complaint is a product insight. Every churn is a pricing model hint. The people who use your product early are doing your research for you — you just have to listen with the same discipline you’d apply to a paid survey.
Distribution decides the model. A good product with no distribution is a research project.