Technical writers are really reporters.
They report on the information they receive, and their writing can only be as good as the raw information you give them. Let's look at how defining the writing project and communicating with your writer affects success of your project. Without a specific audience, your writer may create a technical piece for a management audience or a high-level marketing piece for technical engineers. In either case the writing doesn't match the audience, and the piece loses its effectiveness. If you have developed your key messages and an outline, give them to your writer at the outset.