As soon as you gain control, focus your fire on the tank. Once it's destroyed, move all technicals just south of the base to kill all approaching red guard. You'll now be free to destroy the rest of the base. Don't use your bomb trucks; instead get promotions for your other units by destroying the buildings with brute force. Hotkey all technicals to one group, all tanks to another, and place the bomb trucks in a third group. When the entire base is destroyed, you'll watch a cutscene.

Now you know you can get to a "secret arms dealer". Take your technicals just southeast of your base kill the four red guard then backtrack west. You'll see a path that leads back to the west, where you'll see the dealer. Now you won't need to build an arms dealer of your own, as you'll gain control over it. Research the scorpion rocket addon. This will give your scorpions a rocket attack, which is a good opener on any assault (they'll use it automatically). Build two more scorpions, but don't wait on them - proceed to the next step.

You should now take your bomb trucks to the east of your base, just east of where you fought the red guard. When you see the Chinese tanksimmediately stop ('s') and use the disguise as vehicle command. Use it on the battlemaster tanks. One by one send your demo trucks into the center of the Chinese forces. The first truck will cause severe damage to them all, the second will practically wipe them out. There may be a few left, which you should clean up with your scorpions, saving your third demo truck for later. An interesting thing with the GLA is that after you destroy an enemy, like a tank, you can use a vehicle to pick up cash or upgrades. The enemies your tanks destroyed can be looted, in this way, simply by moving over the dead vehicle and picking up the crate. Now finish off the Chinese base.

Take all your forces north, around the hill until you see a road. If you follow it east you'll encounter a small group of Chinese led by two battlemasters. Focus your vehicles' fire on these then kill off the infantry. You can then head to the south, where you'll find the Chinese speaker tower with some troops guarding it. Kill every enemy here and you'll get some free rebels, which you don't really need. Now take your last bomb truck to the north of the speaker tower area. You'll find the main chinese base. Drive that sucker right into the center barracks to deal some delicious damage.

Now destroy the base with all you've got. It will take a little while but you can familiarize yourself with GLA combat a bit. Once it's destroyed look a the mountain range west of the base. See how it curves to the southwest then stops? If you follow its path you'll see a passage that leads to the north -- take it! This is the path to the dam. It's poorly guarded by a few red guard. Destroy them, then focus your fire on the dam to complete the mission.

User-Submited Tips:

From Vincent VV:

At the beginning you must not use the bomb trucks. When they reach the base, drive a technical to the 'secret arms dealer' and disguise the bomb trucks as scrap cars. All bomb trucks must have the high explosive bomb- upgrade. Drive them to the red guards, which you can see at the radar map. As they arrive, let them attack the dam and detonate.

From Qaman123:

When you gain control, save your bomb trucks. When you get to your base, send a unit to the secret Arms Dealer. Dusguise the bomb Trucks as the SUV by the Arms Dealer and just send them to the dam. No chinese will go for them. Done in like 5 minutes! :D

Gee, guys, why didn't I think of that.