The Necessity of Expansion
If you take two commanders of similar skill and pit them against each other, the one who can generate more resources faster will be the victor every time. To this end, the importance of expanding your territory to new resource patches cannot be understated. Indeed, efficient expansion is perhaps the single most important skill you can acquire in this war. Even if you lack combat prowess, if you are at no loss for resources, you may well defeat your opponent by overwhelming him through sheer numbers. A fast, consistent flow of resources will facilitate this.
It is difficult to generalize and suggest when a commander should expand to a new location. Many variables change the specific conditions under which expansion should become a priority. The rule to follow is that you must try to expand the instant your original position is fortified and your flow of resources there maximized. Locate a site for your expansion base well in advance. If the battlefield permits, try and find a site in between your original location and the enemy so you can advance most of your garrison to protect the fledgling base as it builds up. You are at your most vulnerable when you expand for the first time because you must spread your forces thin, and your resources are low. Make certain you complete the operation successfully by properly scouting the area before you expand to confirm that no significant enemy presence is nearby.
Should the worst transpire and your upstart base fall under attack, know that you may cancel construction of any pending structures to reacquire the resources you spent on them. Ideally, however, you simply must not let this case occur. The primary function of all your expansion bases is to help generate revenue. The more expansion bases you feel capable of maintaining simultaneously, the better off you will be to create them.
Bypassing Restrictions
This is but a simple yet all-important reminder to heed your own common sense: If you find yourself frustrated by the slow rate at which your combat units are being produced, strive to correct the problem. Specifically, build more structures with which to produce your forces. Build as many as you need. A competent Protoss executor needs at least two Gateways producing his ground forces and may seek to establish as many as four relatively early in a battle. A Terran commander seeking to mount a major attack against his enemy needs at least two Factories producing Siege Tanks to amass a sufficient quantity quickly. And even the Zerg, who can build units much faster than the other two species, should heighten their advantage by establishing a second Hatchery within their primary base so that they can hatch six rather than three units at a time.
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An extra Zerg Hatchery within its main base lets the cunning Zerg Cerebrate produce scores of units simultaneously. |
The structures that produce units are relatively inexpensive. Never hesitate to build as many as you see fit. If your resources are growing at a much faster rate than you can spend them, that is more than likely an indication that you do not have enough structures producing units. This same rule applies for upgrades - multiple Terran Armories, for example, may research multiple upgrades simultaneously.
Next: Knowing Your Upgrades 
