Seeking Input for Software Verification Policies?

e8johan asks: "I currently work at a company in the automotive industry. It is importat to ensure quality and for our products we use extensive testing before, during and after the assembly. Now I have been asked to help in the creation of a company instuction for ensuring that all 'in-house' developed software works properly. I have written a short summary describing the essentials such as: "do not ignore compiler warnings", "always describe what the code is intended to do in your comments", "do not assume that all users run in the same environment", etc. I now feel that I need more input, has anyone done anything like this before? How do you test your software?"