I work both sides of the coin. I have a degree in fine Arts, but have been a software guy for many years. I put in an initial design when I make a HTML mock-up

I work both sides of the coin. I have a degree in fine Arts, but have been a software guy for many years. I put in an initial design when I make a HTML mock-up. I tweak it until I think it is good, then start to code the actual functions. As I work with it, within a few days, the constant usage and testing show me what is wrong with my design. I then often iterate, updating the design whenever it starts to annoy me. At the start of the project, this is often once a week. After a few revisions, I slow down, and by the time I've been working with an app 6 months, it is fairly stable. In terms of how you actually make your design, the KISS principle remains valid. It is much easier to add small UI elements to make a page more interesting than to scale back from an over-engineered design.