The Starcraft Command
Tip: Use the Terran buildings' built-in flexibility. Their buildings can be lifted up and placed in other areas--perfect for command posts that run out of resources, or bases that are in jeopardy. They're also great for advancing your front line. As you push an enemy farther and farther back, keep moving your unit-constructing buildings farther up, so that your units can get to the battle faster.
Tip: Make sure you repair any Terran buildings that have suffered critical damage. Due to some faulty power supply modules, once this race's buildings' hit points go below a certain level, they'll continue to erode to the point where they just disappear.
Tip: Build nuke towers on all your bases. Nukes are very, very handy for taking out massive amounts of units in one or two blasts.
Tip: It's important to protect yourself early on; the Protoss' initial units are more powerful than yours, and the Zerg will often be inclined to quick Zergling rushes. Establish choke-points, where you cut off access to your area of the map. Start by building up some bunkers near exits and entry points to your Terran territory, and man them with Firebats in the front bunker and Marines in the two adjoining bunkers behind. By doing this, you'll have some strong defense in the case of a quick rush from either Zerglings or Zealots that won't sacrifice your units.
Tip: It's all about bunkers, baby. There's no better way to protect yourself, or provide a nuisance on the fringes of enemy camps.
Tip: Firebats are good for other things besides bunker duty. They may have a short range, but they hit hard in close-range combat. They're particularly useful in the early stage of a game against the Zerg, because they have a leg up on the Zerglings.
Tip: You should be continually cranking out Marines, the cheapest Terran unit, either for use in bunkers or for use as shock troops. With their ability to take shots at air targets, they go great with large battle groups, especially considering their low cost. In massive battles, consider them expendable and use them as the first line of defense for Siege Tanks, which are vulnerable to air attacks.
Tip: Get your Vulture production going and Spider Mine research completed as soon as you can. Vultures make for great scout units due to their high speed, and they have the Spider Mines going for them as well. Sure, laying Spider Mines is a high-maintenance kind of thing. But it's well worth it--20 or 30 mines laid out in front of your base will create hell for approaching enemy ground units.
Tip: More Spider Mine tricks: Sneak near enemy territory and plant mines nearby. Or plant mines near where you think your enemy will expand. Or plant mines between you and an aggressive opponent as a deterrent.
Tip: Use the SCVs' on-the-fly repair capabilities. When you're moving troops off to a battle, include an SCV or two in the battle group. Once a battle begins, move the SCVs behind the fray, and as valuable units get damaged, retreat them to the SCV bivouac for repairs.
Tip: Use your nukes against massed troops, rather than buildings. First off, troops that are awaiting battle orders are more frequently unprotected, so your ghosts can get through. And second, there's no better way to soften up your opponent and break his morale than by wiping out or seriously damaging his "killer" battle group.
Tip: For several Gamecenter editors, it's all about Siege Tanks. Get these babies built up and upgraded early, and you'll have a lot of fun against weaker foes. Three or four Siege Tanks combined with a row of bunkers and some missile towers are practically unstoppable on defense.
Tip: If you use Siege Tanks, watch the skies, because although it takes a lot to destroy them, they have no protection from air attacks. Use Marines, or better yet, Wraiths, to protect your tanks.
Tip: Whenever possible, place your tanks (in Siege mode, no less) on cliffs or stone walls, and strategically arrange them to get the most ground coverage. This is a very effective maneuver against a Zergling rush.
To Air Is Human
Tip: In air combat, the magnificent Battlecruiser, with its Yamato Cannon, has to be one of the most powerful air attacks of all the races combined. They can create quite an impact in groups of two or three. In large-scale battles, use them to pick off moderately powerful targets. Make sure you retreat them when they've sustained significant damage--they're too expensive to lose, and the Terran SCVs are handy at repairs.
Tip: To kill off Protoss Carriers, group two or three Battlecruisers together with some Wraiths. Target the Carriers with the Wraiths first, and with any luck the Carriers will start taking them out, leaving your Battlecruisers without significant threats.
Tip: The pedestrian Wraiths aren't so pedestrian against ground troops, especially in large groups in undefended map areas with their cloaking field turned on. You should always have plenty of Wraiths on your side, and you should try to have a group of eight or nine of them in your reserves.
Tip: Upgrade your Wraiths as fast as possible. This is especially true if you're leaning heavily on your Wraiths (which you should), because upgrades affect all existing units.
Tip: Use the Science Vessel's EMP Shockwave to disable Protoss shields. It's an awesome (and surprising) way to leave Protoss enemies exposed and vulnerable.
Tip: The Science Vessel is probably one of the more underutilized forms of defense. It requires a lot of energy, but has the ability to defend the buildings or units of your choice with its defensive matrix. When you're attacked, use it to protect your most important buildings--like the Command Center.
Tip: Drop-shipping troops requires a special bit of stealth and timing, but if you unleash forces on either an underdeveloped area or when an enemy is still building up, you can take out lots of important resources early. In fact, if used wisely, you can prevent enemies from building up at a crucial moment, thereby crippling them for the rest of the game.
Tip: When you've discovered prime territory for expansion, don't just send an SCV out to the site to build a new Command Center. If you have some spare resources, and more than two existing Command Centers, pick up and move one of them to the desired location. This way, you can take over part of the map before anyone else.