My primary assumption is that the "look" you are wanting is similar to Command & Conquer, WarCraft, Ultima Online, and so on, either in "straight overhead" or isometric representation. My secondary assumption is that you already have at least the basic concept for your game. These articles will not cover game design in any real depth. Instead we will be focusing on implementation issues.
Data structure and coding examples will mostly be taken from my currrent project, Artifact. Artifact is an Internet-based, client-server, multi-player, persistent-world, real-time strategy game. Artifact is currently in pre-release, with full release scheduled for Fall 1999. For more information and screen shots of the game, check out the Artifact web page: http://www.samugames.com/artifact