Never ask for confirmation of a delete. Always make them undoable. If you can't make them undoable, try harder.
Remember, Undo is the king of interface idioms.
It enables strong actions with a single gesture throughout the interface.
It makes users more willing to explore and experiment.
It enables users to get into flow because they can act with confidence.
It is not a v2.0 feature, or even a v1.1 feature. Build it in from the beginning.