How do you delegate an important assignment to others while ensuring that it will be completed successfully?

How do you delegate an important assignment to others while ensuring that it will be completed successfully?

Before you delegate, ensure the person is capable and committed towards to doing the task.
Break the task into smaller sub-tasks and have milestones/check-points defined so that it is not a final surprise.
Give some working freedom and observe the outcomes only.
During interim review Compliment the individual on the things that you noticed have been done well so that he/she knows the expectations more clearly.

Once the assignment over, have a candida review discussion for the individual to walk you over their modus operandi.