There are literally dozens of Terran builds and possibly hundreds of Cheeses. As a result I'm going to try and lay out a couple of the broad strokes, but unlike Protoss or Zerg these are not going to be succinct build orders.
The three major builds in Terran play are:
Obviously there is a lot of variation and overlap between these builds but I'm going to try and lay out the broad strokes here.
Terran bio revolves around building a Marine/Marauder/Medivac force for a nice timing push. This is sometimes called the MMM build. Openings usually consist of 3 Barracks (sometimes called Rax), 2 with techlabs and 1 with a reactor. A Terran economy can readily support 3 Barracks . The timing push here usually comes at about 40 food with a heavy Marauder/Marine force with Stim. The build continues to evolve into the late game by adding on a Factory and Starport for Medivac support. Medivacs are key to Stim based play, as any force that stims is necessarily at reduced HP for the remainder of the game. Additionally, Medivac's provide for drops which increases the mobility of your army. You can also transition into Bio mech, or add Ghosts on for TvP.
Terran Mech grew out of early hellion harass. This usually involved building one Barracks before going to 2 Factory and pumping out hellions for early harass and then transitioning into a more stable Thor/Siege tank force. This is especially effective vs Zerg players going Muta/Ling as upgraded Hellions are powerful vs Zerglings and Thors do splash damage to Mutalisk. Additionally, heavy Siege tank forces are effective vs Hydra/Roach armies. Top Zerg players (such as Artosis and IdrA) have said that Terran Mech is so powerful it is "Broken" (a term to mean unbalanced) against Zerg. A key point to remember is that the initial Barracks can be used for scouting or to produce Marines (which help an early Mech army).
The 1:1:1 was first popularized by the player The Little One (TLO) and has become the standard in TvT play. The name derives from having one of each unit producing structure: 1 Barracks, 1 Factory, 1 Starport. The synergy that units from these buildings provide have cause this build to become increasingly popular outside of TvT play. The basic idea here is to build a Marine, Tank, Viking force, using the Vikings to give Line of Sight to the Siege tanks (which can fire further than they can see) and using Marines to fight off Air harass.
One of the important points of this strategy is to use Vikings to establish air dominance. In a losing battle, the Vikings can always land and wait for Marine support (as Vikings are an air to air unit). The power from this build comes in its flexibility. Usually 1 techlab and 2 reactors, these addons can quickly be switched, allowing the deployment of Banshees (once air superiority has been obtained) and Hellions, or swapping to Marauders to break a Siege tank grouping. Unless there are serious balance changes in the future a number of SC2 Commentators (Huk, Day9) have suggested that this will become the standard Terran play.
I'll briefly mention a couple of the standard Terran Cheese strategies.
6 Rax into Reaper harass is a popular TvP strategy, as early reapers built from a proxy Rax (a Barracks built close to the opponent) will arrive before the Protoss has Stalkers and thus are unbeatable with good micro.
Banshee rush, especially against Zerg opponents has also been popular as Zerg does not have a staple unit before Tier 2 that can attack air.
Thor drops (often a part of mech builds, or biomech) are very effective. While rushing thor drops can be considered a Cheese, use of them as part of a normal build is present at even the competitive level.
Standard Terran opening is:
- 9 Supply
- 12 Barracks
- 13 Refinery (optional)
- 15 Orbital Command
How to read these: The number indicates the number of Supply you should have when you build your first structure. This number is usually SCVs but may include other units.
Can't rush? Expand!
Base Defense
Terran are the most defensive race in the game, and the best at repelling early aggression due to their ability to 'wall off'. Because supply depots can be raised and lowered like a draw bridge, Terran can create a wall at their ramp that can only be passed by their units. In addition, by walling off the top of your ramp the enemy is forced to post a unit at the top of the ramp just for vision to return fire on your units. This further increases the defenders advantage making it harder for them to retreat and providing a natural choke on their units.
Terran walls are the most effective early game rush prevention in the game, but that doesn't mean they are invincible. Good game awareness, unit mixture, and repairing the wall can often make the difference between a win and a loss when your wall is hit hard.
A pictures worth a 1,000 words :)
Now that you have safely gained access to the mid-game, as you mentioned the next concern is intelligence.
Scouting Techniques
Send an SCV to scout the enemy early
in the game (either after your first
supply depot or after your barracks)
this can prevent you from losing to
early cheese like cannon rush or
proxy buildings.
After creating your barracks at the
wall ~16 supply count create an
orbital command. At around 6-7
minutes scan the enemy base to
determine their tech route.
By posting a single unit at the Zel
Naga towers you gain a solid 20 - 30
seconds worth of warning before an
attack actually hits your wall.
Flying an unused building is also very valuable, however, by the time it actually gets to the opponent they often have the capability of shooting it down. Instead of getting an expense and potentially vital building structure killed, just send an SCV and watch what kills it. You can often spot vital information (in TvT is there tanks? in TvP colossus? in ZvP roaches? expansion? hydra's?) SCV's are the cheapest Terran unit at 50 minerals, but a scan costs 270 (opportunity cost of not picking a mule).
By combining good scouting with a solid defense your chances of losing to an early rush is significantly diminished.
The Early Expand
Because Terran is naturally such a resilient and defensive race, they often have the ability to defend against a much larger opposing force. This leads to a powerful early game expand (generally 1 or 2 Barracks building marines into an expansion). See the image below as a bunker and a tank holds off a much larger force.
By combining the above concepts (walling + scouting) with Terran's natural defensive properties (free bunkers) you can often gain an early advantage and still survive if your opponent attempts to put on early aggression.
Best Answer
Just build multiple barracks with no addon buildings and pump out marines. Build offensive bunkers. You can put addons to the barracks and salvage the bunkers later to push into mid-game. An early reaper rush utilizes tech labs as well that can be transitioned into marauders later.
Your goal of course is to either walk your marines into the enemies mineral line and start shooting. They may pull their workers off or push to attack you, either way marines have a great advantage to just run back and shoot some more with a little micro. You can also take out pylons/depots/overlords with your marines to slow them down considerably by supply blocking them.
So either choose early reapers (which are rare these days) or mass marines and micro them carefully to avoid your enemies early melee defenders (you might have more trouble against Terran though, due to early walls and the fact they also have ranged units).