I mostly like to choose a data structure that's handy for modeling the data I'm worried about first. Then I write code to manipulate that data, including gettin

I mostly like to choose a data structure that's handy for modeling the data I'm worried about first. Then I write code to manipulate that data, including getting it into and out of other formats if necessary. Then I worry about what the application really needs to do with it. Once everything's a presentation or transformation of the central data structures, the code becomes fairly obvious. One I have the data handling and the UI, often the UI is just another case of presenting or updating the data.