Graphics
You can distill a tremendous amount of data into one well constructed graphic. Graphics are the real heart of presentations. Presentations without graphics are called lectures. Below are several guides/rules for using graphics in your presentation.
Pictures.
Pictures can be the best way to document a workflow or specific project. They should be tightly composed to show one subject, color corrected and well exposed. If you want more information on taking pictures for presentations, there are many excellent books or resources on the web.
Use Standards.
Many of the charts and graphs we use in the highway industry have standard forms. Use them as the basis for your graphics. For example, the sieve analysis for aggregates in asphalt mixtures are plotted on a 0.45 power semi-logrithmic chart. You should use the same scale but with much less detail than the standard industry chart. Engineers are familiar with the chart and will immediately recognize the characteristics of the mix. Other forms are standardized, but will also benefit from less visual clutter. Develop your own company standard for these presentation forms. Use the standard detailed forms in the Paper.
Use the Correct Graph.
Time valued graphs are almost universally shown as a line graph. Quantity measurements as bar graphs. Percentages as pie charts. Etc. There are any number of fine books available to help you find the correct graph type.
Consistency Helps Understanding.
Do not mix graph types from slide to slide unless the actual data type changes. Vertical and horizontal bar graphs can both display the same information type. Make a choice and stick with it.
Use the Correct Dimension.
One of the major mistakes made with graphs is the use of 3D graphs to display 2D data. The scale of the graph becomes confusing and distorts your data. If the 3rd axis doesn't have a scale, its not a 3D data type. Use a line not a ribbon; use a bar not a block. We have no problem with 3D pie charts. Pies do have a third dimension.
Scale on Significance not Magnitude.
Another major mistake is improper scaling of axes. Never disconnect an axis to make the data fit the area of the graph. Scale the axis properly. If it still doesn't seem to fit, you are likely using the wrong graph type.
Scale the axis to display significant changes in the data rather than a convenient scale for the magnitude of the data. For some data there is great significance between the numbers 6 and 7. For other data the difference between 1000 and 3000 is meaningless. Factor the scale for easy reading (i.e. millions, x E6, or x 10^6).
Illustrations.
Sometimes an illustration or custom artwork is the only solution to properly presenting a point. We often deal with the very large, such as pavers or milling machines, or the very small, such as laboratory instruments. Both tend to have the details locked behind safety and environmental guards. An illustration is the only way to show how these systems work.
First, decide if the inner workings are well enough understood by your audience to need the artwork. When you do need illustrations or custom artwork, hire a professional. You will find that hiring a talented professional to do the work will yield higher quality and a lower overall cost in both time and money. Your time is better spent building pavements.