What is the best Starcraft strategy

I personally, would say to not linger in gathering minerals and massing in units. Try to build up just what you need, so the computer or other player can't dominate you

If you're versing computers, the best stradegy for all races is this:
Protoss:Build some nexus to block off you're base entrances. Then build photon cannons behind it, the computers dumb brain will try to go for the photon cannons when it cant attack them cause the nexus is in the way. When ur done with that the comp cant kill you(unless they use air units), so just mass produce carriers.

Zerg-same as protoss but use BOTH types of colonies both sunken and spore and build guardians.

terran-Same as both above but with a bunkers and at least two missle turrets(to detect invisible units), mass produce goliaths or wraiths.

If you're fighting a human there IS no best stradegy, as there will always be a player out there who can counter it.