Begin bar charts at zero for a more accurate and truthful comparison of data.
Truncating the Y-axis may lead to misrepresentation of the data that can mislead your audience.
Avoid distorting charts
Line charts are great at showing trends but are sensitive to changes in the size of the chart.
Stretching the height will tend to overplay (or overestimate) the changes or trend.
Stretching the height will tend to underplay (or underestimate) the changes or trend.
Use pie charts sparingly
Keep the number of categories to 5 or less.
Don't use the pie for comparison—e.g. comparing the number of procurements per year
Triple-check that the total value of your pie is exactly 100%.
Don't make things worse by putting the pie in 3D.
Pie charts are great at showing or highlighting one share of the total.
Bar charts work great as substitutes for pie charts.
Use colors deliberately
Use color for communication mostly and for decoration sparingly.
Too many colors can confuse or disorient.
Be mindful of your choices of color so you can create inclusive visualizations—e.g. color-blind friendly visulas, etc.
There are online tools that can help you create color palettes and combinations that are inclusive, beautiful, and just work—e.g. Color Brewer, Viz Palette
Keep right
Align whole numbers flush right to make it easy to find and compare them.
Similarly, you can align decimals usind their decimal point.
More decimal places is not always better
Extra decimal places imply more precise results but are usually unnecessary and distracting.
Round your numbers off before plotting.
Convey your message with both form and function
Removing all artistic elements will make your visualization boring.
Having too much artistic elements may distract the audience from the data and the message it conveys.
Add labels and titles.
Don't use 3D if your data isn't 3D
3D is visually appealing but can make your chart hard to read and understand.
Unless you are plotting something that is actually 3D (e.g. elevation), stick to 2D charts.