Zerg players often win by outnumbering their opponents. This frequently means that a zerg player will need a larger economy to support a stronger force. However, focusing exclusively on worker production can leave you unprepared for enemy attacks, or render you helpless to assist teammates. The following guide aims to help you strike a balance between building your economy and making enough units to keep your army aggressive.
The ideal number of persistent drones – drones that aren’t morphing into buildings – per fully running base is at least 20. Your second hatchery should generally be at your first (closest) expansion area; should your opponents block this hatchery, expanding to a different location, such as your natural third base, will likely be more efficient than trying to wait out your enemies.
Constantly make drones as long as it is safe to do so. Extra drones can prepare you well for continuous expansion.
Scouting is crucial. Knowledge of your opponent's plans will help you gauge how many drones you can produce without becoming too vulnerable. Be sure that you constantly hold Xel’Naga watchtowers with zerglings, spread creep aggressively, and frequently glance into enemy bases with overlords or overseers.
Don’t allow your enemy to scout you. Whether you are making drones or units, you want to conceal your actions from your opponent(s). If they see you making nothing but drones and sparse static defense, they'll know that you're susceptible to attack.
To prevent enemy armies from pressuring you, try harassing them, first with zerglings possessed of the metabolic boost upgrade, and later on with mutalisks. This will keep your opponent(s) on the defensive while allowing you to simultaneously scout the map. If your enemies are not harassing or attacking you, you can safely crank out a bunch of drones.
Don’t forget to keep building while you're harassing your adversary. If you find yourself with many unspent resources after a successful harassment, use your extra minerals and gas to further your goals. Produce key units, expand, make more drones, or build structures to advance your technology.
Try not to lose your units while harassing. If you find that you cannot slow your enemy down, or if you anticipate an imminent counter-attack, you will need your units to help defend.
While developing your economy, you want to make the minimal amount of units and static defenses necessary to protect your vulnerable investments. Every defensive structure (spine or spore crawlers) you create is one fewer drone to mine with. You’ll also need to dedicate another larva, 50 minerals, and build time to make a replacement drone.
Should you spot your opponent making a move to attack you, you should attempt to turn your existing larvae into units or build spine crawlers to fend them off. Placing a spine crawler at your first expansion is generally a good deterrent to early rushes.
Zerg armies are well-served by stockpiling vespene gas, which allows them to construct large masses of mutalisks, hydralisks, or infestors. However, there are two considerations when stockpiling vespene gas: how soon you sacrifice mineral mining potential for gas, and how much gas you use to create banelings. Be cautious in both cases – stockpiling vespene gas too soon can prevent you from dedicating minerals to the production of more drones and defending units, while banelings can be a wasted expenditure of gas if you don’t use them to do significant damage (ideally more than their cost).