Agreed. There are some important other steps as well. It's a bad idea to sell unreliable junk. So having a sense of what kind of reliability testing you need

Agreed. There are some important other steps as well. It's a bad idea to sell unreliable junk. So having a sense of what kind of reliability testing you need is key. Reliability testing should start as soon as possible. This testing often can identify significant problems in the design or assembly that are difficult to model. Things like temperature cycling, damp heat, and high temperature storage at a minimum. Also a big piece of HW design is designing for the whole distribution of parts you might get not just the parts you have now. Will your design fail if you get parts that are at the limit of the data sheet specs? This is where the modeling @FreedomToCreate is talking about is key. Lastly, making sure you really understand the concept of yielded cost. If you get your yielded costs wrong you will be wrapping dollar bills around every product you ship. If your gross margin is below ~35% on a new design you should be worried.