I would start with diagraming the overall process/workflow the app is enabling. Increasingly the "user experience" transcends just the web app, and involves we

I would start with diagraming the overall process/workflow the app is enabling. Increasingly the "user experience" transcends just the web app, and involves well timed SMS messages and notifications. Once the essential UI is defined, I use Balsamiq to iterate on a design, then over-communicate specifications for an Upwork Freelancer to bid on.