Five minutes on Cartography
Maps are communication devices and there are a series of cartographic design tips that facilitate map comprehension. There are also issues of completeness and data explanation that are important to maps. The elements you include on a map depend on the purpose of a map.
Basic elements to always include:
Spatial Reference Information
1) Neatlines help guide the reader to the map features
2) Fill white space, but do not overcrowd areas
3) Consider balance of features on the page horizontally and vertically
4) Consider what is the main objective of the map. Try to symbolize the most important features such that they draw the most attention.
5) Maps are composed of the main map composition area and then extra elements such as legends, scale bars and so on. In general you should frame the spatial data according to the shape of the extent covered by the spatial features. Extra elements should go to the side or bottom of the main map area
Proper selection of colors for choropleth maps is a key component to the readability of a map. Cynthia Brewer's ColorBrewer is a wonderful resource for helping select good color schemes.
Cartographic Design Using ArcGIS 9 - ESRI Virtual Campus Course by Cynthia Brewer