


Here you can improve your Offense, Defense, Economy and Development. Always use Peace Shield if someone tries to attack you and do some research at Research Institute. Do the available Black Ops and try to defeat some renegades for more boosters. Keep gathering more resources and if you have the second queue available to work on 2 building at same time use it and work on the other buildings like oil refinery, metal extractor, chemical plant and all the others.

You can use all the boosters that you have earned doing missions, but for now it is better to gather more resources and be prepared for the next upgrade. As you have noticed, after upgrading your headquarters you always have to upgrade other buildings first before another headquarters upgrade. In the first 12 levels you will do all the upgrades easily enough but the next 4 will be a pain since you need many more resources.
