If possible, edit the colours of maps to match the colour palette of the publication, but check first whether colour has specific meaning, such as in some weather maps.
If the sea is not relevant, leave it white (rather than blue) so that it does not distract the reader. Choose a neutral beige or pale grey for land if this needs to be coloured.
Delete irrelevant symbols, and edit those that can be edited so that they are legible (not too small or large) and consistent with the document colour scheme (again, check for meaning first).
Include a legend in the bottom left corner that explains the colour scheme. List the items in a logical order (eg diminishing size or importance, or alphabetically).
If a map uses shades of the same colour, limit the number of shades to a maximum of 5. Using more shades of one colour will make them very difficult to distinguish (see example below). Other factors that affect perceptible differences between shade intervals include the size of the reproduction and the chosen hue (such as yellow). If you have more than 5 categories within your data, use a colour scheme or introduce hatching patterns.
A map that uses more than a dozen different shades of green, which are largely indistinguishable and difficult to associate with the gradient scale
The same map with the colour graded into 5 distinct shades that are clearly defined by the scale in the legend
