Tactics for Rampart.

If there are no Centaur nests, they usually don't survive until the second week in numbers sufficient to form a strong attacking force. Their job is to hold back the Elves, taking the brunt of the attack (if there's no other way), and finishing off those that the Elves didn't manage to kill. If you plan to break through something very strong, Dwarves and even Treants are indispensable helpers. It's clear that they are slow, but they are only needed for serious battles, and after that (if they survive:)), they are given to the Squire, and the main hero continues on with Centaurs and Elves.
And if I manage to capture a maximum number of mines with the above-mentioned losses, I will be as happy as a child, because in reality, it doesn't always work out so well. You take a mine, earn 5k, buy two heroes with it, and they will earn another 5k each. It's a business :). Besides, they can also find a Centaur nest, from which you can replenish your losses. But if you protect every Centaur, being afraid to attack mines, there will be no point in it. "A rolling stone gathers no moss":)

It's best not to attack upgraded Fairies, upgraded Wolves, and other unpleasant creatures, but if there's no other way, there's a tactic for that (without which attacking them means flipping a coin: morale in the first round means defeat or heavy losses). You hold the Elves in the corner with two evenly divided Centaur squads (or Centaurs + Dwarves), and surround them with single units that will take the first hit, and then shoot with ranged attacks and attack with Centaurs, while not forgetting to also attack the Elves.

You can ask and tell, tell and ask for a long time. Theory is good, but it can't compare to practice. You would be better off learning to play in real games with real opponents. You'll figure everything out faster. For example, Loi plays for ranking, and he didn't even see Heroes until last fall (not to mention online, but in general). And now I remember how he played six months ago, and how he plays now. Believe me, the difference is obvious. He has played more than a hundred online games in these six months (maybe a little more) and has significantly improved his game, winning against strong Heroes players. This is because he didn't just ask, but tried all this in practice with people ;) And it doesn't matter that there will be defeats at first - soon victories will begin ;)