In this position paper we present a set of best practices for workflow design to prevent workflow decay and increase reuse and re-purposing of scientific workflows. MyExperiment provides access to a large number of scientific workflows. However, scientists find it difficult to reuse or re-purpose these workflows for mainly two reasons: workflows suffer from decay over time and lack sufficient metadata to understand their purpose. We argue that good workflow design is a prerequisite for repairing a workflow, or redesigning an equivalent workflow pattern with new components. We present a set of best practices for workflow design and the semantic tooling that is being developed in the Workflow4Ever (Wf4Ever) project to support these best practices.