The following will give you a good understanding of UI design.

Number 3, Designing Interfaces, has a coherent set of principles.

1. [Don’t Make Me Think](https://sensible.com/dont-make-me-think/)

2. [The Design of Everyday Things](https://en.wikipedia.org/wiki/The_Design_of_Everyday_Things)

3. [Designing Interfaces, 3rd Edition](https://www.oreilly.com/library/view/designing-interfaces-3r...)

4. [Nielsen Norman Group Interaction Design: 3-Day Course](https://www.nngroup.com/courses/interaction-design-3-day-cou...)

5. [Apple Human Interface Guidelines](https://developer.apple.com/design/human-interface-guideline...)

6. [A Dao of Web Design](https://alistapart.com/article/dao/)

7. [Usability Testing](https://www.nngroup.com/courses/usability-testing/)

It’s important to practice, not just read. The term is “dogfooding”.

https://developer.mozilla.org/en-US/docs/Learn/Getting_start...

Finally, probably first of all, it’s worth thinking about whether your user interface is harmful to the people using it, and changing if so:

https://www.deceptive.design/

https://www.humanetech.com/key-issues