How one moves a unit in a wargame is, to my thinking, integral to how that game plays and, perhaps more importantly, how to understand the game. Game designers give us clues about the best use of units and potential strategies via the movement rules.
Movement allows you to bring your units to (or away from) combat in a manner of your own choosing. You can maneuver to assault the weakest point of your opponent’s line, make spoiling attacks to prevent his or her strongest units from operating at peak efficiency, or waste your forces in ill-advised sallies against well-fortified positions. Conversely, movement allows you to withdraw to better terrain, cut off enemy supply, and occupy vital territory, furthering your aims without attacking.
Combat is only part of a wargame. One of the hobby’s most venerable publications is called Fire & Movement, after all. Without movement, you’re simply rolling dice to see who wins. At that rate, just play Yahtzee.
One of the most succinct expressions of “how to move” can be found in the Standard Combat System (.pdf) (Multi-Man Publishing/The Gamers).
The SCS movement rules are a distillation of years of “best wargaming practice”—someone who has only played Avalon Hill or SPI games from the 1960’s or 1970’s wouldn’t have much trouble picking up an SCS game.