User interface design improvment for an existing iPhone app

I have an iPhone app available already in the iTunes store. I am looking for a graphic designer/user interface designer which will improve visually the application: - define color scheme - define format for text elements (select font types, size, etc.) - select native UI elements - where applicable - design custom UI elements - where applicable (e.g. buttons) As a result I will expect at least: mock-up, description of elements (colors, fonts, elements size), files with custom GUI elements (e.g. buttons). Please describe how you understand the job, and what you are going to deliver. Some reference GUI designs are required.