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
The 8 competencies of user experience: a tool for assessing and developing UX Practitioners
A UX practitioner demonstrates 8 core competencies. By assessing each team member's 'signature' in these eight areas, managers can build a fully rounded user experience team. This approach also helps identify the roles for which each team member is most suited alongside areas for individual development.
Craft, Leadership
The 8 competencies of user experience: a tool for assessing and developing UX Practitioners
Agile is an iterative approach to project management and software development that helps teams deliver value to their customers faster and with fewer headaches. Instead of betting everything on a "big bang" launch, an agile team delivers work in small, but consumable, increments. Requirements, plans, and results are evaluated continuously so teams have a natural mechanism for responding to change quickly.
Processes, Project Management
What is Agile?
Knowledge
Typography Elements Everyone Needs to Understand — Gravit Designer Blog
Type design may be intimidating to many, with terms such as leading, baseline, kerning, ascender, tail, and many more … The good news is, there are eight basic, universal typographical design elements: typeface, hierarchy, contrast, consistency, alignment, white space, and color. Even a basic understanding of each of these elements can revolutionize any design project.
Typography
Typography Elements Everyone Needs to Understand — Gravit Designer Blog