Consider the dashboard of a car: in it, the driver can see the most important data: speed, RPM, mileage, etc. The dashboard displays decision-making information, in a graphical manner, in a single place.
The information dashboards should comply with the same requirements:
Although not necessarily copying the model of a car! This is a mistake. There are better ways to graphically display information.
So, we take a few charts, some tables and we throw them all together in one screen, right?
But I think the most important thing is that the dashboard tells a story, or helps you tell a story and, above all else, is esthetically simple. No color degradations or images with shading or use of 3D. Imagine for a second that your car displayed your speed with a 3D chart, would you be able to read it so easily? Would you be able to make right decisions? I don’t think so. Have that in mind when designing a dashboard.
At Excelcharts you can get various dashboard examples made in excel. If you need a little more spiritual aid, I recommend Information Dashboard Design, de Stephen Few. A short and easy to read book; ruthless when it comes to tearing down old notions and clear when teaching the principles of good design for dashboards and reports in general.
Although it has some things specific to their product, the Tableau Visual Guidebook is an excellent guide on the basics of producing a good data visualization. The last pages contain a great checklist that you should complete before deploying your visualization.