Once you have control to your tank, you can unlock an achievement early in this mission. As soon as you spot several enemy tanks, destroy six of them to get the "Scrap Metal" achievement. Refer to the video below.
Love the smell of burning steel in the morning
After destroying the tanks, you'll have to switch to thermal mode to spot two more enemy tanks. Take them out the watch the following scenes. Once in control, charge to the enemy fortification and take out the enemies. Remember to switch to your machine gun when dealing with infrantry, specially the RPG soldiers. The rocket batteries will be marked in your map so head there and destroy them all.
The cavalry has arrived!
After getting your new orders, head back out to the desert and hunt down enemy tanks. Next, you'll be ordered to take out the convoys. There will be some tanks here as well so take them out first before moving on to the softer targets.
We'll ruin somebody's day.
Next, head to the highway and join your allies. Continue following him until you reach the underpass. Approach the soldier on foot then you'll need to activate the trigger as marked in the map. Simply run there, grab the detonator, run back and activate it. Once done, go back to your tank to man the .50 cal.
As you move down the highway, keep a look out for enemy RPG soldiers. Also, you can eliminate enemies much faster by shooting at cars and explosive objects beside them. Along the way, a tank will appear in the gas station. Just shoot at the gas pumps and it should be enough to take out the tank. Continue along and wait until a friendly tank gets destroyed by a suicide bomber. Wait for a few seconds and two enemy vehicles will appear. Concentrate your attack and make sure that they're destroyed before getting near. One more will appear to your right; and you also need to take out the enemy RPG soldiers who will take position in the overpass. Wait a bit and mission complete.