Tactics for playing as the Dwarves.

I think it's actually difficult to start with Dwarves; before the gray-skinned bears appear, it's a real pain. A lot depends on whether you get the energy rune. And Karl is the best option here – he has ranged attacks, a cart, and Soldier's Luck at the start... we shoot, cripple, and the Mountain Guards cover us... I only upgrade the Rune School when all the vital buildings are already constructed, closer to the endgame. Of the magic schools, Light is best for Dwarves, but Chaos is easier to manage at the start.
I've also heard about starting with Ingvar, but I didn't like it... In general, for Dwarves to have a successful start, they need either Chaos, or Karl, or Machine Management and money to buy all these machines (fortunately, the forge is a mandatory building in the Dwarven castle).