Scientific software is often hard to maintain and reuse. A major reason for the instability of software is that it is subject to continuous change. This is especially true for software in the scientific context, since the scientific discourse is open-ended. Change has caused difficulties for scientific software developers from the very beginning, and it continues to do so. In parallel, the software engineering community has produced numerous developments that we as research software developers can take advantage of to significantly support our work. This workshop is an introduction on how to bridge the gap between both worlds and introduces practices, methods and principles to develop maintainable software and to make the software development process sustainable. Topics that are discussed are: Design priciples: SOLID & Co. with application examples Design patterns with hands-on application exercise