Having been in senior management and a CEO for many years, I have found that delegating is not only a skill but also an art. You question is very interesting as I assume that in most situations you would be delegating to people more skilled or more knowledgeable about the task or project than you are. A good manager knows their limitations and their role which is to manage rather than do. Therefore the rules on good delegation techniques still apply:
1. Identify the right person or team with the right skills and experience to do the work. It sounds as if you have done this. Write down the reasons that you feel that they will be better placed to get the best results and portray this to the person up front.
2. Be clear on the level of delegation that you are giving to them. There are 9 levels (if you would like to know these, please let me know). This includes a detailed briefing to outline the tasks/outcomes.
3. Negotiate the timeframe, reporting and results. Don't tell, ask - then double the time they estimate. Most of us underestimate the time anything will take. By providing the person with extra time they will feel much more positive about the tasks and be confident on delivering the outcome.
Negotiating the timeframe, reporting and results is the most important step. Never dictate this as you really want a good outcome and this will only be achieved if they are part of this decision.
Please call me if you would like some more practical help.