The author describes various procedures to minimize risks involved in prototyping of analogue and mixed signal integrated circuits at external fabs and compares different approaches of minimizing NRE costs using Multi Product Wafer (MPW) or Multi Layer Mask (MLM) service and describes procedures of parallel processing of different design versions on one mask set. Furthermore he gives some guidelines for efficient production ramp-up and yield optimization and opens discussion on the optimization on back-end (assembly and test) activities for efficient prototyping. Further to that the author discussed several online tools which are provided by foundries from the engineering phase through production.