Defining a project is by far the most important step in the design process.   The direction a design takes will vary depending on what is expected.   Some projects require more definition than others.   Obviously the extent of the requirements have a impact on the project costs.   Here are a number of issues that may be important to your project.  All the items in this list are not required in most projects.  However, there may be others that are important to you and this is the time to discuss those issues.