Instructions
Search extensively. Special items do not appear on your map, and they are often inconspicuously hidden.
Use other vehicles. Although Warhawks are your primary craft, the layout of the level and location of enemies can make you more vulnerable. You can use jeeps, for example, to navigate past air defense turrets and other obstacles.
Get help. Whether in single or multiplayer mode, use your teammates to provide cover and eliminate enemies. Some items are difficult -- if not impossible -- to get until friendly players clear the way for you.