Many people are asking:
Where is the dummy's guide to gathering qualitative or quantitative feedback in order to inform product vision/feature decisions?
Noted internet luminary J.P. Rainsberger, for example has asked:
Where's the dummy's guide to gathering qualitative or quantitative feedback in order to inform product vision/feature decisions?— ☕ J. B. Rainsberger (@jbrains) December 7, 2016
And it can certainly be a challenge to get started on such a daunting task.
One great place to start is the work of Amy Hoy and Alex Hillman around "Sales Safari" and I urge you to dive deep into their work. They've put a video online showing an earlier version of their sales safari lesson.
Another place where this will be covered in more detail is the book I am hastily throwing together, which spends quite a bit on the mechanics (and pitfalls!) of qualitative research, as well as pointers on quantifying your findings.
Now I think you should sign up to be notified when the ebook is ready. It steps through the process of finding a good idea, validating it, turning it into a product, then selling, marketing and supporting your product. It's written for people just like you.