Warcraft III: The Frozen Throne/Human strategies

Against Human
Archmage first, build as many Spellbreakers as possible, and add a few Priests. Second hero MK. Since the enemy probably builds the same units your best chances to win are either better micro, higher hero levels, a lucky creepjack, or a perfectly timed attack on the base, when you know that the enemy is not there. If an expansion is possible to build and hold long enough that you actually make profit from it, then build it.

Against Orc
Archmage first, build as many Sorceresses as possible, and add a few Priests. Buy a Beastmaster from the tavern as second hero and try to win through the summons. Try to level your heroes as much as possible and attack before the enemy TC reaches level 3 or the Farseer reaches leve l4. Because if that happens his Shockwave/Chainlightning will kill your Sorceresses and Priests in no time. Only build an expansion if you are 100% certain that you can hold it (Lost Temple), else it delays you too much which gives the orc time to level his heroes.