billybgame: I am just on the very first scenario of the Original campaign. Where you have to take 3 castles to the N.
Since it looked like you needed some guidance, I figured I'd record myself playing through this scenario.
Here's the video. Please bear in mind that I did get lucky here and there, so it might seem like I had it really easy. I beat the level during the third game month, which is kind of late in this particular case. But anyway, I hope this'll expose you to a few basic and advanced strategies. Below are my comments next to the times they occur within the video.
00:16 ~ I left my Halflings in town for the time being, as they will slow the hero down.
00:18 ~ Splitting up creature stacks can be done by selecting them and Shift + clicking on an empty slot.
00:58 ~ I was lucky enough to find a Barbarian hero for hire. Barbarians and Knights have higher Attack and Defense than magic-based heroes (Sorceress, Warlock, Wizard, and Necromancer), so try to hire one.
05:43 ~ These Trolls guard the entrance to your territory. In all my years of playing this scenario, this was the first time the enemy didn't break through and invade. Perhaps I got lucky this time, because it's normal to have unwanted company by the third or fourth weeks.
07:06 ~ Since I'm ending my Barbarian's turn inside the town, I garrisoned all the slower creatures (i.e. Halfings and Rocs) and left the Boars intact. This ensured that the Barbarian would begin the following turn with as many movement points as possible.
07:46 ~ Barbarians and Knights do not begin with Spell Books, so remember to purchase one!
11:26 ~ I usually recommend taking Gold from treasure chests. It's tempting to choose EXP so you'll level up faster, but the free Gold can really help you afford buildings and creatures.
12:49 ~ This Wizard is transferring reinforcements to my Barbarian. Using multiple heroes really saves you time and legwork.
19:14 ~ I'd normally choose Pathfinding, but since this particular map is all grass (easy terrain), Leadership is more useful.
24:34 ~ When fighting groups of ranged creatures like these Halflings, it's very handy to have two stacks of flying creatures (e.g. Rocs). If you can position them in between two ranged creatures, you'll force them to fight hand-to-hand. That'll prevent them from shooting at your own fragile ranged creatures.
25:21 ~ One thing you'll notice me doing often is transferring my Barbarian's slower creatures to a nearby hero. Once again, this is so the Barbarian will be able to move farther the next turn. Just remember to give the Barbarian's creatures back to him when he needs them.
26:05 ~ I'd forgotten that my initial Wizard was carrying the Thunder Mace, which was the starting bonus I chose at the beginning. Here, I made sure to transfer it to my Barbarian. Note that I didn't transfer the Halfings or Rocs back to him yet (in order to keep him moving farther).
29:33 ~ Both here and at 30:15, I got very lucky. Creatures offering to join you is a rare treat, but unfortunately, we cannot rely on this happening all the time. Zombies and Dwarves are very slow, so you'll see them mostly relegated to my scouting heroes throughout this video.
30:50 ~ This is a bizarre playthrough. It's amazing that my opponents are eliminating each other while leaving me alone.
36:29 ~ I decided against battling these Centaurs because they're the same speed as my Rocs. A Centaur stack was likely to move before my Rocs could tie them up, and I didn't want to risk losing any Archmagi.
37:38 ~ I hoped that adding 34 Dwarves to my Barbarian's army would prompt the Gargoyles to flee, but my plan backfired. Thankfully, the ensuing casualties were relatively minimal.
40:35 ~ There are usually better secondary skills to choose than Eagle Eye, but Navigation is useless in this scenario.
49:32 ~ The enemy Barbarian player has been eliminated. As you know, it's usually this guy who pushes through the Trolls and threatens us during the first game month.
56:23 ~ Much like with the Centaurs, Trolls are the same speed as my Rocs. I decided to play it safe.
1:05:12 ~ Magic-based heroes aren't the strongest generals, but their spells really hurt...
1:09:29 ~ The Xanadu gave my Barbarian +1 to Attack, Defense, Spell Power, and Knowledge since he's Level 10.
1:09:57 ~ I wasn't expecting to field Dragons or even Giants during this playthrough, but the opportunities arose.
1:11:17 ~ Sadly, I forgot that my Barbarian didn't have the Wisdom secondary skill. No Level 3+ spells for me.
1:18:51 ~ I decided to do some resource trading. In order to buy a few Black Dragons, I needed more Gold.