Small, but sometimes important, tactical tricks.

I don't know if you can call it a trick... Well, various tactics with mines – like luring enemies onto them, or placing them so that they are guaranteed to land on specific tiles (the rest are blocked by troops; it's especially good to target a catapult during a siege – they land neatly in front of the rows of besieging units) – I guess everyone knows that...
Or, in an early battle against demons, split the imps into several squads – let them steal all the enemy's mana:)
There are also other tricks – you attack with griffins against a strong squad of high-level neutral creatures; you constantly strike from the sky and attack the enemies with your hero:) It's especially good if you have the "Guardian Angel" skill: if there are losses, you deliberately lose the entire squad so that it can be resurrected. Or you can attack a squad of slow enemies with a very small squad, break it into several parts, and attack the monsters with your hero – this is how I captured a city defended by 25 demons with 7 peasants and a level 1 hero (during the battle, they were in several squads! it took some effort).
Everyone definitely uses Fury to its full potential:)
Furthermore: for spellcasting units, the strength of spells does not directly depend on their numbers; the most powerful in terms of the ratio of the number of units in a squad to the damage of the spell is a group of one spellcaster. Therefore, at the beginning, we split the mages into several squads – and the spells are two or three times stronger than if they were in one...