Five principles of good flag design.
A comprehensive guide to flag design from the North American Vexillological Association (NAVA) can be found here. Another great piece put together by www.milwaukeeflag.com can be found here (even though I strongly believe Maryland’s flag is an example of a great flag). More simply refer to these five principles when designing a flag:
The flag should be so simple that a child can draw it from memory.
The flag’s shapes, colors, or patterns, should relate to what it symbolizes.
3. Basic colors
Limit to three purposeful colors, in a standard color set, which create good contrast.
4. No Lettering or Seals
Never use writing of any kind or an organization’s seal. Seals were meant to be seen on a page and viewed closely. Flags are meant to be seen from a distance and fly in all directions.
Avoid duplicating other flag designs as a flag should emphasize its own identity.