Units have attributes and the system is a little more complicated than Warcraft 3.
If you look at each unit it will have one or more of the following descriptors:
- light
- armored
- biological
- mechanical
- massive
- psionic
For example a marine is a light biological unit while a siege tank is an armored mechanical unit and a marauder is an armored biological unit. This is something you will have to memorize with time but usually you can guess which will apply just by looking at the unit or in doubt clicking on it. These are easily viewable on the HUD just below the units description in the center of the screen.
Now each unit may have a bonus against one of these armors making it a good hard counter. You can see this bonus during game by selecting the unit and viewing the HUD in the center of the screen. It will list the damage of the unit and any bonuses it receives against units of a particular type.
For example, Helion's have +dmg vs light armor and are great for killing zerglings, a light biological unit. An Immortal has a large +dmg bonus vs armored units and is a great counter for other armored units such as marauders, siege tanks, roaches or stalkers.
Blizzard has said there will be tutorials in the released version of SC2 to train players for multi-player combat. Part of those tutorials will be explaining by example how these hard counters work and which units to build to counter your opponent.
+1 for the dream analogy!
Like dreams, there is a good explanation of why you are living your game in slow motion, there is always one thing slowing down everything else. In the case of dreams, it is your brain, that actually dreams faster than your perception. That's why you seem to be slow, because the dream is actually faster than what you perceive.
For StarCraft, this is another problem. I discovered by studying replays that faster players remove one very large part of the time you may take in your game: controlling the army.
As an unexperienced player, you might not be familiar with unit balance. So when sending your 12 zerglings againts those 4 zealots, you don't yet know the outcome. I'm sure you expect some victory, but can you trust this expectation enough to actually leave your zerglings do the work without you?
I often find myself microing too much when dealing with large overpowered army. Yeah, I have 24 zerglings and they meet 1 zealot. Really, no need to micro them, just return and take care of your base!
Your problem may be the same...
Best Answer
I never considered pro-gaming myself or know anyone closely who live of it, but since I watch (maybe waaaay too many) videos, interviews and listen to podcasts (mainly State of the Game) I'd like to give some ideas around training in video games, especially StarCraft.
First of all: Stay healthy
Whenever a progamer gets asked what is important besides playing huge amounts of game he states something like your body is very important, you need to be fit to be able to think fast, play fast and grind endless games. As far as I know, nearly every player in e-sports does some workouts or runs to stay in shape, e.g. the guys from Evil Genius go to the gym and lift weights regularly (Geoff stated this in some SotG episode).
Youtube video: "Evil Geniuses: Bench Press"
Training houses
Especially (but not only) in South Korea most (all?) of the teams have their own training house. It makes things much easier when you have an environment where you can focus at your work with other people that do the same job. Also it is important to have someone around you can talk to if you have some problems, discuss ideas and test things. Usually they also have a dedicated coach who helps with certain problems, keeps an eye on special people and all this - like its known from every other professional sport.
Although specific methods may alter from team to team.
I heard in the oGs-TL house players have an house-intern league: Everyone has to play almost everyone else once a day. This not only gives you motivation since you want to improve your position but playing many different opponents gives you some wider vision and experience than only training over and over again against one specific person and matchup.
Back in November 2010, Giantbomb.com made a Video tour through the oGs-TL training house and also got some players and the oGs-coach for some interviews. For me its pretty interesting what they say about training and life there.
I think most team-houses have more or less strict schedules when players have to get up, hours to practice and relax and workout. At least 8-10 hours training each day should be really common, maybe it goes up to 15-16 hours before important events for some players.
Training at home
This should be the case for most American and European players.
They usually live on their own and make their own schedules without a coach or sth. The training is different for everybody. I consider every pro player also has some "closer" training partners for each match-up to discuss and try out certain strategies/builds, even if he is not in a team (White-Ra).
Methods
Laddering - grind as many ladder games as possible.
This gives a wide variety of opponents and strategies, especially some cheesy plays and gimmick tactics your teammates maybe never consider. It also helps to keep up/improve mechanics.
Test/Improve Build-orders
It can be done against computer opponents, in custom maps (YABOT anyone?) or against practice partners. It is purely time dedicated to make a build perfect for a strong early/midgame or against certain cheeses/all-ins.
Special Preparation
Before important events or matches where they know their rival in advance, players most of the time concentrate on the enemies styles. They analyze replays, think of ways to encounter the playstyle and maybe abuse it. Commonly one of the training partners tries to play the same way as the opponent so you can practice especially against that.
I heard in the training houses of Brood-War teams they usually had one coach for each race or even match-up. Coaches were also there to create new strategies/build and teach them to the player so he could focus on making the execution perfect.
Artosis made quite a couple tours through pro gaming houses and uploaded them to youtube - if you're really interested also watch some interviews with players and coaches.