In the options you can change the Power Ranking bar to be color coded for threat level. If they mad at you they will show up red or orange. Helps you from wondering why you just got pulled into war.
You want to get your hands on some influence early on. [Prestigious locations], It mellows out the A.I. and can be worth a lot in trades as the game goes on.
Even though when you level up the new spells dont look like there worth it, do it. Its worth it later on, and they only show up at random. You may get stuck with generic level ups at next level.
Make sure you have a mage that picks as many magical level ups as possible. Its worth it in the end. The early spells dont seem all that great, but the final ones are rockn' (still need more).
You can plan on getting your heroes upto level 7-12+ on almost every game you arnt getting clobbered in. You can plan accordingly.
Play on the hardest level first. Play it until the AI smashes the last stone in your last city. Then go back to normal. It wont take long.
Initiative and encumbrance are way more important then they may seem.
Dont sell inventory items you dont need at the beginning. Keep them as a piggy bank for the unexpected. If its not coin you cant spend it. Believe me, you'll need that 23 coin at some point to save your life.
If you have the option place a city on or near a forest tile. You can build a lumber mill to help with production. Same way with rivers.
Dont think your city is safe from that group of ogres because they've just been wondering around for 10 turns.
Dont quit if your getting crushed. Take it like a man. u learn a lot that way.
Spell mastery effects only the % chance that a spell will have an effect on the target, not the mana cost of the spell.
Clearing the forest helps you move in and out of town a little faster early on.
Get all your champs on horses as soon as possible (a bit into a game). You can buy them from AI territory if they've done the research. They can geto hot spots in a rush.
Dont plan on your first dragon encounter going that well.
Oh, and last one. Once you have 2-3 towns, take inventory of the possible resources you have available in the area. Those are going to be your bread and butter. Plan the rest of the game around those resources.
War between the AI's is often an opportunity. check often who is at war with who.