Start every bar chart's y-axis at zero. Truncating the baseline turns a +4% change into a fake +400% explosion — the single most common way charts mislead.
Match the chart to the question. Bars compare values, lines show change over time, and pie charts fall apart past ~5 slices. The question picks the form, not your taste.
Aspect ratio rewrites the trend. The same rising series looks flat when squished and like a spike when stretched — balance it so the average slope sits near 45° and reads honestly.
Maximize the data-ink ratio. Strip gridlines, drop shadows, 3D skew, and boxed legends, then label the line directly. Every remaining pixel should carry data.
Color is encoding, not decoration. Use one hero color to spotlight the series that matters, and choose categorical, sequential, or diverging scales to fit the data type.
Title the chart with the takeaway, not the metric. "Revenue flat since March" tells the story; "Quarterly revenue" makes the reader hunt for it.
Do / Don't
Do: Start every bar chart's y-axis at zero, no exceptions.
Do: Pick the chart type from the question you're answering.
Do: Spotlight the one series that matters with a single accent color.
Don't: Truncate or crop an axis to exaggerate small differences.
Don't: Add gridlines, shadows, or 3D effects that encode no data.
Don't: Reach for a pie chart when you have more than five slices.
The Design System Blueprint
An 11-page visual guide to consistent, scalable UI: colors, typography, spacing, components, motion.
