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.
Proof of concept in software development is a controversial topic. The person that came up with a software idea is usually convinced of its relevance. And stakeholders usually don't want to spend time on something that is not even going to be included in the final product.
Startups, Biz Dev
Proof of Concept in Software Development
Knowledge
The Jobs-to-be-Done Market Discovery Template — JTBD + Outcome-Driven Innovation
The Jobs-to-be-Done Market Discovery Template is a framework that entrepreneurs, startups and managers can use to define a target market through a jobs-to-be-done lens. Using it mitigates the risk of targeting a phantom or overserved market as it directs the user to define a market around an underserved job.
Startups, Biz Dev
The Jobs-to-be-Done Market Discovery Template — JTBD + Outcome-Driven Innovation
Knowledge
Domain Expert Interview — UX Knowledge Base Sketches
Domain Experts / Subject Matter Experts / Industry Experts have invaluable knowledge that you can (and should) apply during your UX process. Domain expert involvement is not an alternative to UX research, and a domain expert is certainly neither a “user expert” nor a designer.
Interviews
Domain Expert Interview — UX Knowledge Base Sketches