As a founder you'll be bombarded by "advice" sometimes unsolicited. You'll be challenged by "experts" who sometimes interestingly have little experience in your industry. They'll question your business, your model, your style, your strategy etc. Some will say you should do X before Y and another will literally say the exact opposite. Focus. Focus through the noise. Listen, but be firm yet flexible in your stance. Trust yourself. Test and learn. Fail. Fall. But always get up and push on.