The ten rules, and the six mistakes that ruin a map

The ten rules

1. Landscape format, A4 minimum, A3 for a broad subject.
2. A central image, five centimetres, three colours minimum.
3. Five to seven main branches, never more.
4. One keyword per branch, in capitals, on the line.
5. Curved branches, thick at the base, thin at the tips.
6. One colour per main branch, kept across its offshoots.
7. Strict hierarchy: each level is one further degree of detail, never an item of the same rank.
8. Pictograms on the key elements, at least three per map.
9. Linking arrows between distant branches, for cross-cutting relationships.
10. One page only. If it overflows, the subject has to be split into several linked maps.

The six mistakes that ruin a map