I'm playing as Axel.
In the first week, I upgrade archers (only to red ones) and split them into 4-5 stacks, build training halls (+7), and upgrade the capitol. To level up the city, I build a market and peasant huts. The hero needs to capture the sawmill on the first turn. Starting from the first week, I train 7 peasants into archers (if the difficulty is maximum, you can manage without the +7 archers). The hero needs to get the "Experienced Commander" and "Master Counterstrike" skills as quickly as possible.
In the second week, I upgrade the training halls (+13), upgrade the capitol (you should upgrade the capitol for humans as soon as possible!), and build a guild of mages. It is also vitally important to capture the gold mine as quickly as possible, and take most of the treasures in gold.
After the guild of mages, we build a monastery, then save up for a stable and an order of paladins.
So, as you can see, the point of my method is to create an army consisting only of red crossbowmen, knights, and angel/seraphim.
In the late game, split the stacks with knights into 2-3-4 and reduce the stacks with archers to 4-3-2.
And here are a couple more tips for my strategy: 1) NEVER upgrade the monastery and barracks (where lamellar armor units are produced), and 2) don't build griffons; use monks and later lamellar armor units only for upgrading to knights, and don't put them in the army!
And 3) use training halls EVERY week and preferably to the maximum!
That's all...