[nick-garfield]

If you're in the "talking with customers" phase, you should also check out "The Mom Test" by Rob Fitzpatrick.

http :// momtestbook .com (EDIT: I just noticed this is an http site... breaking up the link into pieces for now. Sill recommend Googling the book)

The tldr; is that as soon as you tell someone about your idea, it's going to bias their subsequent answers. They're going to lie to, try not to hurt your feelings, want to get rid of you, etc. So if you're trying to validate an idea, the most important rule is "Don't talk about your idea".

What "The Mom Test" recommends is to instead ask prospective users about their lives and specifically to recall individual moments when they had the problem your idea will supposedly solve. With this "unbiased" recollection, you (as the entrepreneur) have to put 2 and 2 together to figure out if people 1) really have a problem and 2) are open/looking for a solution.