Verify Again and Again
After doing something, Verify, ask a friend to crosscheck, verify again.
Wait there is more ...
Then ask somebody who does not like you so much, to check or test it and offer critical comments.

delabs design service - Circuit and product design
Otto, Manuel and Me
No these are not Modes of Operation in another tongue. I met these Gentlemen in an Online Ergonomics and Usability Hangout.
It was just Otto, Manuel and Me.
Engineering a Responsible Product
Affordable - Usable - Safe - Maintainable - Durable - Green
Green - Low Energy Consumption, Biodegradable, does not pose an Hazard to Environment, does not hurt Flora and Fauna.