What Resources should I Stockpile?

This will all depend on the individuals play style as some people are agressive while others are defensive. It is important regardless of your play style that you level up your hospitals whenever possbile and research the 'Medical Building' so you are able to increase the amount of wounded troops they may hold. Remember that if you have more wounded troops than hospital capacity the remainder of your troops are killed.

Consider building the tier 1 Traction Missle Launchers found in the Artillery Factory as these cannons have 20 load which is the highest load and they also allow your gatherers to collect resources for a longer time period. These tier 1 Traction Missle Launchers are also cheaper and more efficient than other tier types such as Commando, One-Man Copter and Recon Tank so try to get enough of them to fill your marching capability.