Use the human ability to see connections between separate parts of a system. The Gestalt Laws of grouping (Wikipedia) provide tools that help us avoid the disconnect found between flush buttons and toilet seats in air plane toilets.

Build products that help us improve the world a bit, just like the toilet with small and big flush do. But build interfaces that do not deteriorate over time and that provide clear options.

Build accessible artefacts with buttons that we can all push and info we can all understand. Highly accessible products, like the single handle tap, have become standard and are used by us all.

Make the important system states obvious, just like the water level is in the alien faucet. Designers can never coerce behavioural changes – changes can only come from within persons – but we can induce by choosing what we highlight.

If your interface needs instructions, you have failed. Use usability tests and other qualitative methods to understand the problems in your interface and fix them. The user is (almost) never wrong – the problem is in the artefact.