I forgot to mention that I didn't explore the dungeons much because the surface was quite inconvenient, and I spent the entire game on the surface, clearing my lands. And when it was time to go down, I just happened to stumble upon Homm (I should have gone into the lower tunnel; maybe I would have ended up closer to his castle).
I also didn't find any of the cool artifacts that Homm mentioned. There were some good ones on the surface, but it was still difficult to choose between them. Maybe I shouldn't have taken the Lion set, which gives bonus defense, into battle. I don't know. And I also took a teleportation scroll instead of a +5 shield, although it lowered initiative. In duels, the teleport works differently than in other games. It doesn't give the enemy a turn; it doesn't seem to add anything at all, maybe because it's a scroll.
And it's a pity that I didn't have time to level up properly. I was just a little short of getting inspiration and defense.