Capture as many cites, airports, or anything that gives you money. Then, make as many rockets, artillery and anti-tank units as possible and place them in the woods, ruins, or anything else that will give you cover. When the enemy arrives, rain fire down on them.
Unlock the following medals by performing the corresponding tasks:
MEDAL - HOW TO UNLOCK Gun - Get five medals for Talon Gun/Nest/Meteors destroyed. Maps Cleared - Win on 150 maps. Maps Played - Play on 150 maps. Multiplayer - Get four medals in multiplayer/Wi-Fi categories. S Rank - Earn fifty "S" ranks in Campaign mode. Tank - Produce 200 or more ground units of every type. Time - Accrue 50 hours of game play. Units Destroyed - Get 50 medals for units destroyed. Units Production - Get 50 medals for units produced.