Each design choice on your website should not only look good, but be driven by the objectives of the project.
UI design process
Typography, colour and imagery are key in this process. Individually they evoke emotion, together they are extremely powerful in achieving a goal. Your businesses branding and identity also weigh in at this stage, although I often seek to complement, rather than let it dictate the direction.
Once a typographic hierarchy, colour pallet and tone has been set, common page elements such as buttons or cards can be designed. I spend a lot of time ensuring consistency and harmony across all UI elements, attention to detail is something I take a lot of pride in.
Depending on the project the UI design may take the form of a style-guide to complement the wireframes, or a detailed set of visuals that build on the wireframes, showing how each page will look at popular device resolutions.