Dieter Rams' design principles applied to software engineering

Be ruthless in removing any obstacle between your users and the best value thay can get from your application. Well designed applications are the fruit of many failed iterations, each proofed by real users. Be sure to observe your users as they interact with your application. Think deeply about every action your application performs. Be as strict and demanding with your application as you are towards other people's. Consider the energy profile of your application as it grows. Once your application is "Barely good enough", it is complete.