Designing parallel systems in a correct way is difficult. Transformational  design of systems guarantees correctness by the correctness of the transformations,  but is often tedious and complicated. We discuss different transformation  strategies to guide the designer from the initial specification to different implementations,  tailored to different architectures. Strategies give rise to simpler transformation  rules, point the way in the design trajectory, and allow for the reuse of proofs  and transformation steps when deriving optimizations and variants of algorithms.  