What are Starcraft strategys

If you have the game, use the manual, if you don't here's some guide:
For Terran, medic-marine-firebat are great.
For Zerg, send unites in this order: zergings, hydralisk, lurker, mustalisk for each squad.
For Protoss, use physinic lightning (speical attack for High Templar) to zerg unites, then send bunch of zealots in.
These will help you. (these strategys sometimes not work and don't use against online players. They already know these tricks!)

The best one for computer players is to block off your base entrance with defensive buildings, then build these units and rush for each race;
Zerg-Guardians and scourges/devourerers
Protoss-Dragoons, carriers, or archons
Terran-Goliaths

For online play, i always play as protoss so here is my strategy;

Start off by getting another base FAST; this way you have another base in case your main one goes to hell. Then, build maybe 10-12 high templars, and CONSTANTLY send them in to your enemy base via shuttles and take out their mining units.(probes, SCV's and drones). Then build photon cannons outside their base to prevent them from attacking. Also keep an observer in their base. In the meantime, stock up your base with photon cannons and dragoons and zealots so you can defend your base with your main strategy. Now start building Reavers, and have your zealots and dragoons ready. Use shuttles to drop the reavers off in their base, so they can cause as much destruction as possible. Your enemy will head for the reavers, and as soon as they do, using your observer to tell, rush in with your zealots and dragoons. Works almost every time.