Grand Theft Auto: San Andreas Walkthrough

With the escort vehicles in place, it's time to steal an armored car to act as the legit money-carrier. But first? Something to transport it.

Head to the military fuel dump, marked by a yellow blip on your radar.
As you approach the fence, wait for the humvee to pass and open the gate. With it open, drive through and run over the guard directly to your left.
Steal the fallen guard's gun and take out the pursuing guards around the corner to the left.
Enter the warehouse.
Several guards will be hiding and waiting to gun you down. Stay ducked behind the containers and shoot down the guards in the rafters high above.
Make sure to use the M4 gun, as it will have the necessary range for you to take out many of the guards farther down the warehouse floor.
If you need extra health or armor, they're located just in front of the containers where you came in.
When you've finally killed all of the guards, head outside and take out the guards waiting around the corner.
Make your way up the staircase to the top of the building, where more guards will be waiting.
Head up the next set of stairs and turn right. Ahead, you'll see a red marker. Walk toward it.
Taking control, shoot down the approaching helicopters.
With them destroyed, head up the stairs to the waiting transport helicopter.
Now, it's time to pick up the loot. Head toward the armored car, marked by a blue blip on your radar.
Once you arrive, hover close and press A to magnetize the lift and take control of the car.
With the car dangling, head to the Aircraft Graveyard, located by a yellow blip on your radar.
When you arrive, drop the car slowly at the designated red marker spot.
With the car in the spot, land the helicopter nearby in the designated red marker spot.