One StarCraft 2 strategy has tested near perfect from players who have implemented it when playing as the insectoid Zerg race against Terrans. This StarCraft 2 strategy enables you to launch an early but effective attack before your opponent is able to defend themselves or even react in many cases, so let's look at it now.
Whenever playing against Terrans, you'll find that they'll typically build walls straight away to keep your zerglings from having a chance at an early swarm. Using banelings with speedlings is the appropriate StarCraft 2 strategy in this case and is amazingly effective.
To get the most from this StarCraft 2 strategy, be sure that you are most effectively assigning your drones to minerals. Typically you should be using 3 drones per mineral to most efficiently get the resources you'll need from it.
You'll need to collect a lot of gas early on for this StarCraft 2 strategy to work, as well, along with spawning pools and extractors. When the spawning pool is ready, build a queen and have it cast Spawn Larva on your hatchery. Now build a banelings nest, get your zergling speed upgrade, then continue to build as many zerglings as possible.
When you're ready, position your units right outside the wall. Make sure you're out of your opponents site and go ahead to morph a few zerglings to banelings and send them in to dismantle the wall. Then quickly send in the zerglings through the hole and attack your opponent's units and workers after that. Even during the attack you should still be building more zerglings with the rally point being their base to continue sending them in as reinforcements.