One of the more common problems when setting expectations is when the manager doesn't clearly define in her mind what the deliverable will be. That ambiguity sets the employee up for failure.
The way to avoid this failure is to take the time up front - before setting the expectation with the employee - to clearly define the deliverable in your head. This forces you to think through all the variables - is there a specific message you want to deliver, what about format, what are the variables for the data, etc.
Also think about how strict you will be on the deliverable. If you want it so look a certain way, say so. If you are open to the employee being more autonomous, say so. But only if that is what you really want.
When I point this out to people, the follow-up question is usually "isn't this micro-managing?" No, it is not.
Micromanaging happens when you tell them the how - first do this, then talk to Bob, then do that. Setting clear deliverables is setting the individual up for success, not micromanaging them.
There will be times when you have to be incredibly prescriptive - it has to be done a specific way. There will be other times when you can give the employee more freedom.
Last thing: if you didn't clearly describe the deliverable and the employee hands you something that is subpar - that is your fault. Admit it and apologize. Then take corrective action. Hiding it from the employee doesn't help.