The first step in the process of creating any sort of design is writing what’s called a design brief. This is simply a document that gives both sides a clear understanding of the project’s goals and how they are to be met.
You may not have been through this process before, but your designer has, so let him take the lead. For the client, the writing of a design brief consists basically of sitting through an interview.
When it comes to the project itself, he’ll want to know what your goals and expectations are, what your budget is, when the project needs to be completed, and whose approval is needed at every stage. He’ll need to know if you have any already-determined brand guidelines, and who else he might be working with to complete the project—copywriters, photographers, programmers, etc.
One reason this is important is that without establishing the nature and scope of the project, the designer can’t estimate its cost. But there’s another critical factor that is often overlooked: it might be that what you think you need isn’t really the case. Every design project needs to be conceived as part of an overall marketing strategy; and it’s possible that the best solution the client can imagine is not actually the right one. An experienced designer can help his client to understand why, for instance, using social media could be more effective than a direct-mail campaign (or, vice versa).
The actual questions included in a design brief, and their wording, will differ from one design firm to another, but their intent is the same: to provide the designer with the critical information he needs in order to do his job.
Here, for instance, are the questions Asheville Design Works uses in its design briefs. Most other firms use questions which are at least roughly similar.