I actually designed a dwarven society once that was based on the 18th-19th century British in India. In other words, they were... jerks.
First step was to take advantage of their advanced metalworking skills to make exceptional weapons and armour for humans. Second step was to scout the nearby human kingdoms for civil war, resistance movements, ect. Then they would proceed to go out in the world as traders and sell their weapons to one side or the other in exchange for extremely punitive trade agreements, generally paid for with IOU's. They would also send dwarven troops to shore up their favored side.
By the time their side won, the new king was little more than a puppet. His forces were utterly dependent on the dwarven metalworking and training. The dwarves would then call in their markers and demand huge quantities of goods that they couldn't get themselves, namely hops, barley and meat.
