Basically, list some user stories. Then draw some diagrams based on those. Regularly head out for some coffee with pen and paper and write up some notes. I've

Basically, list some user stories. Then draw some diagrams based on those. Regularly head out for some coffee with pen and paper and write up some notes. I've been developing a personal technique(mainly aimed at games, but general enough to apply to apps) I've been calling "cycle modelling" - which depicts user stories in a visual way, using feedback loops and (implied) narrative arcs - they are used as building blocks to achieve the core goal of the game or app(e.g. "edit photos" or "rule a kingdom"). The complete product is described as a composite of many intersecting arcs and cycles; even a rough model seems to help a lot in clarifying the design and features.