First, you should give a short, suggestive name to your project.

Hint: multi-project version will always show your current project's name at the Current project: combo box in the toolbar. At any time you will be able to create/add a new project to your current pool of projects by simply pressing the New button at the right of the drop-down box. All projects in the same pool will share resources/calendars/etc.

Generally for internal use, you may also assign a coded name to the project.
If you can, establish the responsible project manager, a project client and set the estimated date for the project start.

Make a concise description of the project scope. The scope statement will be an input data for the work breakdown structure you'll define later.