User interface technology has advanced rapidly in recent years. Incorporating new developments in existing systems could result in substantial improvements in usability, thereby improving performance and user satisfaction, while shortening training an d reducing error rates. Our focus is on low-effort high-payoff improvements to aspects such as data display and entry, consistency, messages, documentation, and system access. This paper provides guidelines for managers and designers responsible for use r interface reengineering, based on the experience we gained from six projects, and compiles our observations, recommendations and outcomes. (Also cross-referenced as CAR-TR-767)