From my experience, I too had the problems in finding the reliable suppliers as there are lot of unexpected quality issues and delays. We were distributing physical products and the supply chain was quite difficult to manage due to high percentage of defective goods. two additional challenges: -costs associated with trial and error, especially when forming initial team or signing arrangements with new partners (marketing / advertising, product suppliers). On the hindsight, it would have helped to find the right consultant / insider to suggest the right sources. -not pivoting earlier. The reception of the early customers for some products was quite negative. Instead of hoping to improve the product down the line, the right choice should have been to pivot earlier to focus on more profitable and perspective streams. Hence, most important resource is actually time.