Bear in mind that I normally only play SC against my friend Adam, who likes infinite minerals maps (where each geyser and patch of crystals is worth 50000). Also, the map we normally use is Hunters. So we rarely have to worry about draining our start point of resources. However, to use some of these tactics, it is necessary to grab other bases often just for building space. Plus, of course, only one SCV can harvest a mineral patch or geyser at a time...
As Terran:
Get three or four bunkers built and full as soon as possible.
Next, start building factories. Make about 4 Siege Tanks to back up your bunkers (don't forget to research siege mode). Start researching vehicle firepower upgrades.
Once you have enought minerals coming in, and about 5 factories, start churning out Goliaths. Build more factories. At the height of its power, my base usually has about 16 factories churning out Goliaths at top speed.
So, with about 30 Goliaths arriving per minute, you hit the supply limit fairly quickly. What do you do? Get 'em moving. Just tell 'em all to attack the centre of the enemy base. Eventually, you'll batter right through their front lines. Put in a Science Vessel or two to spot cloaked units. Carriers and Cruisers last an average of five seconds against that many Goliaths. Guardians? Hah.
As Protoss:
Fill the entrance to your base with photon cannons. Leave a probe there so you can rebuild any cannons that get shot. Send a probe out and start building cannons at the entrance to an enemy base too...
Get a few Stargates up and build some Carriers. Expand your base and find a place where you can build at least twenty Gateways. Do it. Build Dragoons. When you hit the supply limit, send your six or seven Carriers off with your attack force and keep building Dragoons. If your Carriers die, never mind. This just means you have more supply points for building Dragoons...
As Zerg:
Build sunken and spore colonies initially, and get about 36 zerglings built too. Research Burrow, and burrow two groups of Zerglings some distance in front of your defences. About Siege Tank range, in fact...
If you're playing Brood War, make some Lurkers too, and put them where your Zerglings are. Then move your Zerglings out to Siege Tank range of the Lurkers...
Get a Hydralisk Den, and an Evolution Chamber or two. Research weapon damage upgrades. Evolve to a Lair, and built a Queen's Nest. Make some Queens if you want. They're good at scouting out enemy bases with their Parasite ability.
Start building Hatcheries in an open area of your base. You'll need about 24 if you want the other players to crap their pants.
Or be like me, and build 36.
Build a Nydus Canal. If you're fighting Zerg, and you've parasited one of their units at their base, try and build a Nydus exit on their creep. In their resource field for preference.
Start churning out Hydralisk and Zerglings. Evolve to a Hive, research Adrenal Glands, and build EVEN MORE Zerglings. Build an Ultralisk Den and some Ultralisk. They cost a lot, but they soak up Tank fire quite well. About 12 should be enough.
Attack the enemy bases, one at a time. Using your whole force. Don't forget to build more creatures as they die. Send a few Overlords too.
Operation Overlord (or, How to be Really Annoying):
If you're on a map with plenty resources, and the enemy likes using units with special abilities, and he tends not to assign them to groups...
Cover the battle lines in Overlords as your force surges forwards.
You'll need about 400. Good luck trying to manage them.
If you want, select about 60 of them to fill with Hydralisk. Not only is the enemy going to have a hard time killing the transporter Overlords, he won't be able to coordinate the defence against the Hydras due to the sun being blotted out by your Detectors. Throw in some Guardians and Mutalisk just to keep things nice and hot.
Or, swap Zerglings for Hydralisk and cast Dark Swarm over the battlefield too. So the enemy can't stop your transported force until they're on the ground, wereupon ranged weapons won't work against them, and he can't see any of his OR your ground units under the transporters...
