While I am by no means a pro player, I have 1,300 wins, so I do know a thing or two about SC2. I only play Terran, and have refined my strategy some. Here’s my standard build order:
* SCV x 2 – mining
* SCV to build depot
* Depot is built – build refinery
* SCV x 3
* Refinery is built – build Engineering
* Divert 3 SCV to gas mining
* More SCVs (I’ll have 21 by the time I’m full speed)
* Engineering is built, build depot
* More SCVs
* Depot is built build second refinery
* Base upgrade to fortress
* Refinering is built divert 3 SCVs
* the SCV that built refinery goes to build 2nd base
* Divert one SCV to start building Barracks
* Divert SCVs to build turrets by the truckload, while building more miners on my bases.
* Build Factory, then Armory.
Upgrade tech as often as possible.
In the end I’ll have 2 bases (or 3 if opponent is a slow, strong building type), 2/3 Barracks, 1 Factory, 2 Spaceports. And maybe 2 Engineerings if I hv the time. I’ll build 50 infantry units (mostly Marines, Thors, tanks mostly for defense), 20 banshees, sometimes some Battleships. I might skip banshees for a change and go Battleships all the way. Or if the opponent is Terran and builds Battleships, Vikings by the truckload: 2/3 spaceports building 2 Vikings each simultaneously. Amazing how 20 well upgraded Vikings can tear apart Battleships…
There are adjustments made to this strategy depending on who I’m fighting — not just the race, but the actual person. Some dudes I seem to see a lot and know how they fight. So I have a better idea of what (not) to do.