First, fight easy enemies. Do NOT buy anything except for specials(whirlers, flailers, that kind of stuff), something to accompany them and training. If your special is ranged, buy a slow, but powerful close-ranged unit. If your special is close-ranged, get a mage. To get cash more quickly, I suggest you don't try to win really fast, but kill a lot of men before winning. Once you have done so, kill the demons before they get too strong. Then, the rest is really easy.
 "Adapt or Die"){kind=icon}
 "Solipskier"){kind=icon}
 "Cube Colossus"){kind=icon}
 "Sydney Shark"){kind=icon}
 "Enigmata"){kind=icon}
 "Epic Battle Fantasy 2"){kind=icon}
 "Little Wheel"){kind=icon}
 "Cargo Bridge"){kind=icon}
 "Warlords: Call to Arms"){kind=icon}
 "Straw Hat Samurai"){kind=icon}
 "Learn to Fly"){kind=icon}
 "Epic War 2"){kind=icon}
 "Minions"){kind=icon}