PMF is usually the tricky one. You should focus and talk the people you are trying to sell your product to even before you build anything. Starts with asking and identifying if they even have a problem you are trying to solve, how are they solving it today, is it even important to them … You can get sooooo much info just by talking to you potential customers, users … And, it’s really mind-boggling how few startup founders ever really talk to their customers.