Besides all the typical startup recommendation, I’ll advocate for something about talking to customers. Everything else is secondary. - Mom Test
Talking with customers is great start - partly an art and science. Unfortunately I did it wrong. In 2012, I had an idea and found two initial customers after calling 40+. talked with these two continuously till the product matures. They are super supportive, they gave all problem they face, exited to use the product as well. gave us good feedbacks and improvements, After 3 months of development, we showed a demo to other customers, very few shown interest. During our post analysis, we came to known that, these two customers have built a project for them. They've completely taken us away from a product to project. customization for few customers is also a bad thing to do. (they have paid me, what I need, but still I missed the great niche product, failed to scale to few thousand userbase with only common features). I should have talked and engaged with more customers and built only core features.