While talking about UX principles, I in my product always would go for the following:
Fast : My product should response to any input that has been given by user in sub-300 millisecs
Assistive: You should always give user something to react to, don’t force them to generate their own content
Clear and concise messaging : Always, make sure you’re guiding your users to respective paths on a regular basis. People don’t want to stay on and stray around!
Simplicity: A 1% PM knows how to get 80% of the value out of any feature or project with 20% of the effort. They do so repeatedly, launching more and achieving compounding effects for the product or business.