Be sure of yourself and reframe your thinking to where it's not trial and error but, it's trial and inevitable success. Once you have your focus on what you are doing and your goal for your business or start-up, that conviction will allow you to see whatever error or mistake you make along the road as a lesson to be learned towards that inevitable success. If I was speaking to someone I would let them know that everything is trial and inevitable success. There are no errors or mistakes, only lessons to be learned. Keep progressing, and don't expect perfection.