In this paper we present an incremental and user-centered process to create suitable and usable user interfaces. Validation is done throughout the process by prototyping, the prototypes evolve from low-fidelity to the final user interface. Applications developed with this process are more likely to correspond to users' expectations. Furthermore, the process takes into account the need for sustainable evolution often required by modern soft- ware configurations, by combining traditional software engineering with a user-centered approach. We think our approach is beneficial in its scope, since it considers evolving software beyond the deployment stage and supports a multi-disciplinary team.