(1) Ask a simple question "Delete?" (2) Don't use many words when 1 will do. "Cancel" "Delete" (3) Don't use words when an icon will do. (4) Don't use

(1) Ask a simple question "Delete?" (2) Don't use many words when 1 will do. "Cancel" "Delete" (3) Don't use words when an icon will do. (4) Don't use cognitively conflicting symbols and colors. Red be cautious, green it's safe, but deleting something can be dangerous in either direction, safe in either direction. A better mental model is action vs inaction, then it's more clear to highlight the response that causes an action. (5) Avoid blocking interfaces altogether. Avoid interrupting the users flow. Perform all actions immediately, but only ever offer recoverable actions. Undo is not the only choice, and probably not the best for things like entire documents. Like loading a file, delete is often not meaningful in the undo stack (though it can be). Another paradigm is moving an item to a differentiated group, such as trash, an undisplayed group or a low rating. This approach is idempotent and allow things to be recovered out of order (it's also easer to implement than undo especially asynchronously). It can also be it's own valuable feature like edit tracking for word processors.