Simplify!
The biggest frustration was a screen where you'd choose a subscription product based on geography. Instead of a confusing grid of fifty choices, I introduced a simple drop-down presented in alphabetical order, which then presents the user with a cleaned-up view of further choices to make. By reducing the number of elements on the page, the user knows where to focus and can understand clearly what the next steps are. On release, we saw an uptick in completed registrations. As a major added benefit, the engineers who implemented UI changes substantially improved the codebase, so the process now runs faster and can be more readily experimented with to further improve the user experience and meet business goals.