With many of the game's puzzles punishing a player at the slightest misstep, Carlsen stated that "it's important that you also treat him nicely." In other words, while death is frequent, it's also entertaining and educational. Ideally, players learn something about the puzzle with each death.
Another philosophy: Make sure the correct solution is "fairly easy to execute" and that incorrect solutions are obviously wrong. Making incorrect solutions obvious aids players in discarding them from other possible solutions, nudging them toward the correct one. After all, there's no better motivator than grisly death.