This guide isn't for everyone, if you start reading and you have no idea what i'm talking about then you probably need some more playing experience, I'm creating this strategy guide in hopes more of the pros will read it and get as good as me so i'll have some hardcore challenge online. Like I said it's not for everyone.

The key strategy to winning in Warcraft 3 lies in the ability to equally build, upgrade, produce units, protect your base, and level up your heroes all at the same time in a fashion that allows some gold/lumber to be saved for specific, and necessary things at the exact time they will be needed, all the while maintaining your army. (Bear with me, that was the hard part) To help you better understand what I mean, Im going to explain to you an example.

-How to flawlessly beat the computer using the humans on the first custom map (Booty Bay)-

Chap one (Maintaining your city while producing a small expedition team)
Select humans and keep everything else default, leave the computer's race at random (Doesn't really matter, the computer sucks on normal). Now the first thing you when the game comes on is grab three peons and send them to the gold mine, grab one of the remaining two peons and build a altar of kings (hero building), and the last one builds a farm. Now quickly select your town hall and produce three peons and set the rally point on an area where you want your barracks, when the peon is produced click on it and make it build a barracks, now set the rally point of the town hall on the gold mine (You'll need 145 gold to build a lumber mill), if the farm peon finishes have him build another farm, also when your altar peon is finished send him to the gold mine and produce a paladin hero. Now that you have five peons mining gold (max amount) Concentrate on producing peons to mine trees, build 2 or 3 peons and set the rally point on the trees, as soon as you have 145 gold send one of your tree peons to build a lumber mill near the tree harvesting site. While your waiting for the peons to be created or whatever if your barracks peon finishes make a footmen and send him to the trees, if the farm one finishes have him build another farm.

Chap two (Go time: Quickness is key element in hero training)
When the paladin comes out of the altar automatically set the barrack's rally point on the paladin and send the hero about halfway down that little strip of land towards the encampment of Trolls (note: first make yourself familiar with the map: booty bay, on easy if you have to) Click on the paladin's level cross+ and pick the healing spell as your first ability, at first it's better to heal your army then worry about your hero's health, he'll be fine until he learns the 10-second invincible spell.
---make at least one more footmen sometime amidst this--
--Make your farm peon build another farm--
--Make a couple more peons and make sure rally point is on the forest--
Now once you have at least your hero and two footmen send them into the troll encampment at the bottom corner of the screen and click on your base, click a tree mining peon and have him build a blacksmith, go back to the battle your guys should be fighting if or if not have them attack the higher level Troll Priest, he's the one who will be healing the units, once he's dead the battle is practically over.
--first make like three more footmen (so you'll have 5 accompanying your hero)
--then if money provides make a couple more peons to mine trees
--Make sure your farm peon builds another farm (This should be 5 now)
--If your blacksmith peon finishes upgrade your footmen swords, if you are rich enough (like 400-200 after the sword upgrade) then upgrade their shields as well
SOMEWHERE amidst all that town crap you have to have finished the battle with the trolls, picked up the treasure and sent your team to the next fight with the knolls (at the bottom, towards the middle) and made sure that while fighting you constantly healed your footmen and made sure your hero was ok, if he starts to red line get him the hell out of the line of fire or your fucked.

-ok I need a second of not working on this strategy, kinda like how one would take a wc3 break to smoke some marijauna or hump a large piece of furniture, or eat, piss, shit, sleep that sort of thing-

Ok send your team up to your second gold mine, this is where your expansion will be.
- If you have enough lumber and gold upgrade your town hall to a keep, if not make 2 peons to mine trees, make sure all available peons are mining trees
-make another farm
-Produce two riflemen and a footmen
-Upgrade your footmen and your riflemen if you can
Ok at the gold mine, make sure you learn your level two spell with the paladin, make it the invincible spell. Activate the pink spell and attack the level 4 troll priest with everyone, make sure to keep your guys alive with the heal spell, you should be ok, pick up your treasure and head towards the middle of the map where the fountain of mana is (important) provided your hero is not red-lining, if he is then get close but don't engage the enemies
-Return to your base in the meantime and check up on your base
-First send a tree mining peon to the second gold mine and save enough money to make a town hall
-Build a tower if you want
-When you get your keep make like three peons and send them in the forest
-Upgrade to advanced lumber harvesting and advanced masonry
-Make one or two more farms depending on how many you have (You want like 7)

At the battle kill the enemies and take the rock stone or whatever, it will summon a rock golem, if at any point you encounter your computer enemy summon that rock golem, after you kill them get the treasures and charge up your mana, then send your guys north to the goblin lab.

-Now make your second hero: The blood mage (expansion required), set the rally point on your other hero
-make sure your peon is building a town hall at the expansion, when he's finished send him to the gold mine and create 4 more peons, set the town hall's rally point on the gold mine
-produce an even amount of riflemen and footmen so your army will be at about 12 or 13
-Upgrade your units at the blacksmith