It's quite a large topic, but the different steps could be : 1. formulate the problem of what you're aiming to solve, and the customer segments who you think h

It's quite a large topic, but the different steps could be : 1. formulate the problem of what you're aiming to solve, and the customer segments who you think have this problem (lean canvas / business model canvas can help you there) 2. ask questions to people part of your chosen customer segments and verify they have the problem 3. create a solution (MVP) to solve this problem 4. demo it to them and verify it solves the problem in a way that makes them pay :-) Ash Maurya goes into a lot of details about this process in "Running Lean" (highly recommended). The general idea is to test assumptions to convert them from hypotheses to facts, using a loop of build->measure->learn.