You are not an expert of everything, so input from others is essential. Ask many stupid questions and count on the experts to put you down. Don’t be discouraged and make sure you understand their point of view. Even the experts don’t know everything, but they are experts of something you aren’t.
I’ve often experienced when receiving advice that the expert goes out of their field of expertise and mainly express their personal opinion of your venture. Gather the facts, ignore their personal opinions and evaluate the information. Don’t expect them to completely understand what you’re doing. You probably don’t completely understand it yourself.
If you’re very special
Sometimes you get blinded by your brilliance. If everyone*, friends and family excluded, tell you it won’t work. You really have to question yourself more than once why, how and by what degree it won’t work. Perhaps you can improve your crazy solution into something really useful. But don’t quit your day job just yet.
* Most people will actually try to be nice even when they think your idea stinks. Listen carefully to them who plead you to quit your insane venture.