Terran strats
General strats
*Use bunkers in leapfrog tactic, as some people call it but I'll refer to it as Bunker bed. Build them 1 after another and eventually into the enemies base. While the front one is being built the surrounding ones will protect it. This is usually only successful against Zerg since they have the Creep.
*Build a Barracks and then fly it over behind an enemy base and build men to attack him. It isn't great but it is better than nothing.
*Place bunkers in tight places where not many men can fit through. This can do a lot of damage if done correctly.
*This next one is extremely important. Hotkey your Comsat Station(I prefer #0), this way you can get a Sweep without having to go back to your building. If you need a sweep real quick, this can be the difference between life and death.
Defending
*Place Spider Mines outside your base. It can work as a tipoff if they are attacking but it can also do much damage if they are closely packed. And a lot of Mines just in front of your bunkers or front defense will wipe out entire armies on ground. Usually one mine alone will obviously do practically 0 damage.
*Build Bunkers filled with Marines and Missile Turrets and place Seige Tanks behind them. But if you want to go further you can place a Supply Depot in front of your Bunkers. Some people might attack the Depot and if it's ground attacking you they'll have a harder time getting to your bunks. This is very difficult to destroy.
*If you're playing AGAINST Terran and notice the person is making a large amount of Spider Mines send out some of your cheapest men to just walk around and set them off. If they are in bunches it is likely that they will all detonate on one cheap little man.
*Another strat to use against Terran is whenever you have almost killed their base try not to kill their Nuclear Silo(s). This way you can either build yours there or move one to it. Check it out and maybe you'll get a free Nuke. You will be able to use it!
