To create beautiful UIs, the most important rules to follow in UI design are:
Put yourself in the shoes of the user-to-be.
Respect the user’s time, the new ones and the ones who are familiar with your app.
Design buttons, prompts, colors, copy, fonts, controls, and menus such that they all feel like part of the same cohesive program.
Go for simple UI designs and remember not to overload the information that you provide.