I still fondly remember this game... I played it when it first came out and enjoyed it very much. I remember how my sister used to be annoyed with my crosbowmen captains screaming 'Fire!' every time before they shoot
As someone said here, it was very hard game, becauce Games Workshop Warhammer rules were implemented completely so (like in the table top one) a bad role of dice (virtual in this case) could make a difference between winning and losing. You could've played the same mission twince, use completely the same strategy and lose one time and win the other. Or score an overwhelming victory once and barely win with heavy losses the other time. That was another thing that made the game hard - since it was one continual campaign, suffering heavy losses in one mission could mean that you wouldn't have enough forces left to win the next one. Especially since you weren't able to replenish losses after every mission, but only certain ones.
I have to brag here that I managed to finish the game without cheating, thought only once. It still involved a lot of reloading of saved games and replaying certain missions until the best result was achieved (and sometimes even going back two missions), but I didn't use the hex editor. I was a bit disappointed with the way it ended (storywise) but it was a still great game to play.
Tips: The strongest unit in your army is your amber wizard. His Amber Spear spell is great for killing enemy characters (shamans, seers) and monsters (trolls, rat ogres) while his Flock of Doom deals with large blocks of enemy units. Before starting the battle (after positioning your units) don't press the start button until Wind of Magic scale is up to the maximum then quickly inflict as much damage as you can with your wizard. Note that he doesn't have the Flock of Doom spell at the beginning, so keep replaying the mission when he's about to get his level until he gets that spell
And make sure you protect him from the close combat.
Your next stronges unit is your Grudghbringer Cavalry, especially after you pick up some useful magic items with it. They are very effective when they charge and even more if they hit an already engaged enemy unit in flank or rear.
When using your war machines (mortars or later cannons), make sure that you fire with them only as much as you need. In other words, once you see that you are winning the mission just stop firing. That way you'll eliminate the risk of misfiring at that stage. Trust me, there's nothing more frustrating than crushing enemy and then loosing a mortar to a misfire when trying to destroy a few skaven that were already running away.
Finally, you'll notice that all the missions are scripted in the way that the enemy's starting possitions are always the same in a mission and their reinforces/ambushes always come from the same spot. Use that to your advantage when replaying a failed mission, to assure that possitions of your troops counter those of enemy's. You can even use your mortars to shoot at a spot where you know an enemy unit is, even if you don't see the enemy.