[FarAway Pretender]

Yeah, I find myself erring on the side of scripting cautiously, so a General doesn't end up in the melee until a turn or two after the footsoldiers arrive. Just position him directly behind a big block of infantry that's slower than he is, and then make him "Hold" two turns longer than they do (since heroes get up to 5 scripted orders and the "Hold & then Attack" option only delays 2 turns, this is easy). He misses out on some of the early killing, but he also (more importantly) doesn't die himself, which is a lot more important if you're trying to secure some Heroic bonuses and/or pad his stats with a little experience.

I don't play much MP, but my impression is that they just hold off, assembling various collections of magic items, until a hero is near-invincible before risking anybody in a battle. Once you get into the MP mid-game, I think there are enough tactics/killer combos figured out that it gets a bit more formulaic.