Never use a warning when you mean undo.
Your first try will be wrong. Budget and design for it.
When you are solving a difficult problem re-ask the problem so that your solution helps you learn faster. Find a faster way to fail, recover, and try again. If the problem you are trying to solve involves creating a magnum opus, you are solving the wrong problem.
To the user, the interface is the product.
Design is the beauty of turning constraints into advantages.
Every time you make the user make a decision they don’t care about, you have failed as a designer.