This is such a great topic for interface design. It’s very easy to fall in the “design by committee” trap, so knowing how to articulate design decisions is crucial to have your designs implemented and not tossed away into the discard pile. As a matter a fact, I highly recommend reading this book dedicated completely to the topic: Articulating Design Decisions http://www.amazon.com/Articulating-Design-Decisions-Communicate-Stakeholders/dp/1491921560