It's probably your familiarity with HoMM3/AoW that's throwing you off, since Disciples plays rather differently. There's not too much you can do in terms of tactics during the battles, so it tends to come down to picking a good troop lineup, then leveling them up to be stronger than your opponent's army. Most of the game is spent hunting down wandering mobs for experience and loot so you'll be prepared when you encounter the enemy; multiple heroes are actually a liability, as dividing the experience means each hero will be significantly less powerful, plus you can only carry one hero between missions in the campaign. Tactical elements mostly come from spell use on the overworld map, and different types of mana allow you to cast these spells (hence needing to capture resources beyond gold).

I loved Disciples1, but unfortunately disciples2 is just too hard. Treasure guards always too strong, Turn left, its hard, turn right, its hard do this, or do that, hard hard hard. I did manage to master it but it is such a grind, i just got so tired of it really, there is no joy here, just walk away, that's what i did.

check this out: http://www.gamefaqs.com/pc/926265-disciples-ii-gold-edition/faqs/22142
found here: http://www.gamefaqs.com/pc/926265-disciples-ii-gold-edition/faqs

my favorite (so perhaps easiest?) race is the Dwarves. hitpoints + armor spells + Son of Ymir = carefree doom for all capitals (in the sagas anyway). a Hermit or two will help with your lower initiative. go for an armor banner and/or potions to supplement the spells. just play as a Warrior lord (for the 15% healing bonus in between turns), choose the fighter or ranger hero and you're set. seafaring and chant of hasting can be life/city savers and help you dominate the resources

the beauty of D2 is that each race has its, um, disciples and they in turn may have very different ways of playing that same race. so if you're at all intrigued by the game, give it a bit more time. it definitely has the potential to grow on you

That guide helped a lot, I understand it better now. The combat and rod-placing just really confused me, it's so different than any other TBS I've played. Thanks!