You might want to read The Mom Test if you haven't. Or well, many of the books on market validation. The Startup Owner's Manual was the last book I read on the

You might want to read The Mom Test if you haven't. Or well, many of the books on market validation. The Startup Owner's Manual was the last book I read on the topic because I didn't need any more after that. Lean Startup is popular too but I haven't read it personally. Questionnaires are cheap but often inaccurate. People will encourage questionaires and landing pages because they're so cheap, but most people who say they'd buy something don't and frequently people will say they won't buy something that they would.