Delegate achieving a specific outcome, don’t delegate a process.
Assume that the task has more than one solution. Especially multiple ones that you could not even imagine. So don’t expect the job to be solved in a certain way. There is nothing worse for the person you are delegating to, than going onto a quest to guess what kind of solution you had in mind.
Try to delegate the task with the level of difficulty slightly above that a person is used to do. This way, the person can learn something while doing it.