Define the question
Instead of starting with “I want to invent a smart device,” ask which problem it solves, for whom, and how you will know the solution helps. Write down one assumption to test first.
Build the smallest useful test
Start with a sketch, a simple prototype or a user conversation. Choose a low-risk test that produces a clear observation. Decide what you will measure in advance so you do not redefine success after seeing the result.
Document, then improve
Record what happened, what surprised you and what you will change next time. An unexpected result can lead to a better question. Do not test medical, electrical or hazardous experiments without qualified supervision.