Jakob Nielsen's 10 general principles for interaction design. They are called "heuristics" because they are broad rules of thumb and not specific usability guidelines.
Usability
10 Usability Heuristics for User Interface Design
Knowledge
User Interviews: How, When, and Why to Conduct Them — NN/g
User interviews have become a popular technique for getting user feedback, mainly because they are fast and easy. Use them to learn about users’ perceptions of your design, not about its usability.
Interviews
User Interviews: How, When, and Why to Conduct Them — NN/g
Colour contrast between text and background is important on web pages. It affects some people’s ability to perceive the information (in other words to be able to receive the information visually).
Microinteractions play a large role in our digital lives, even if we don’t always notice them. From the time your phone’s alarm wakes you in the morning to liking your friends’ posts on Facebook to the notifications about new emails and Instagram messages—we encounter microinteractions all day.