I undestand product vision, business goal & target audience with product stake holders. I make sure requirements are smart - specific, measurable, agreed upon, realistic and time-based. Gain clarity if there is any doubt.
I usually think how a user uses a system to accomplish a particular goal and defines the features to be implemented and the resolution of any errors that may be encountered. Organizing functional requirements, modeling the goals of system user interactions, etc.
Deep dive into detailed pixel perfect mocks to get actual feel of the application. Iconsider the requirements as proposed by the publisher and begin to put together a model of what the finished product might look like. Create clickable mock-ups in invissionapp and so.
I make detailed UI guidelines and specifications that can be leveraged by development team to implement actual application. The design specification include all necessary drawings, dimensions, environmental factors, ergonomic factors, typogaphy, iconography, etc.
Devil is in the details and I strongly believe in the same. I provide all the respective UI assets and work very closely with developers to achieve perfection in the interface. Ultimate goal is provide a fit and finished product to end users.