First, the convoy should have at least five vehicles and they should have extra armor plate or Kevlar blankets attached to protect the crew. The troops in the convoy should carry lots of ammo for their weapons (this means a dozen or more 30 round magazines for each M-16, and as many 200 round belts of ammo for each light machine-gun and several dozen rounds for each M203 40mm grenade launcher.) Get some AT-4 bunker buster rocket launchers if you can. Rig up ring or pedestal mounts for light or medium (7.62mm) machine-guns. If you can get .50 caliber machine-guns, install them on ring mounts in the lead truck.
American troops in Iraq have quickly developed procedures and tactics to counter road side bombs and ambushes by hostile Iraqis. This has made attacking American convoys a lot more dangerous to the attackers, and reduced U.S. casualties considerably.
Your largest truck should be in the lead, ready to push through a roadblock if that seems likely to work. The lead vehicle should have an NCO or officer trained to make quick decisions on whether to drive around a barrier or push on through. Troops should all be assigned a direction to watch while the convoy is moving. A training area has been set up in Kuwait where troops in moving trucks can practice firing at targets. If ambushed, convoy troops must know to get out as much firepower at the enemy is (or is likely to be) as quickly as possible. The Iraqi attackers are usually not very disciplined, and their attack often falls apart if it is met with heavy fire from the trucks.
It's also important that convoys check with the commanders of areas they are passing through, to let them know when the convoy will be in the area and to get radio frequencies and other information so the convoy can call for help from local troops if there is an ambush. The local commanders can also often arrange to have any of their troops or aircraft (including UAVs) escort the convoy for part of the way. The local commanders also know better who the bad guys are in their area and often have information on where ambushes or roadside bombs might be. It's common practice for combat units to have a QRF (quick reaction force) ready to go at all times to help one of their patrols, or a passing convoy.
Military Police often escort convoys, usually forming the advance and rear guard. The idea advanced guard is two heavily armed hummers moving 300-500 meters in advance of the convoy. The advance guard checks out suspicious items (possible roadside bombs or men waiting in ambush.) If possible, another two hummers should follow the convoy by the same distance, for Iraqis have attacked the rear vehicle in convoys with machine-guns and RPGs. For this reason, the last vehicle in the convoy should always be one with armed troops facing the rear. If someone suspicious appears from the rear, blast them. The rules of engagement in Iraq have been aggressive, allowing troops to shoot when in doubt, even if an innocent Iraqi gets killed from time to time. This also encourages Iraqi drivers to stay a respectful distance from American convoys.
American trucks move thousands of tons of material along Iraqi roads each day. Most of it is moved by troops who do this regularly. These troops receive training before they are assigned to convoy duty, and are briefed before the convoy moves out. On any day, only a few percent of the convoys out there will encounter any hostile behavior (usually rocks thrown at them.) Actual ambushes are rare, and the combat troops and MPs are always looking for roadside bombs and armed Iraqis trying to set up an ambush. Most of the roadside bombs and ambushes are discovered this way, and neutralized. But it's only because of these careful preparations that the American casualty count has been kept so low. The Iraqi attackers suffer far more casualties. American intelligence knows this because they monitor the fees the attackers are often paid to make these attacks. Week by week, Iraqis demand, and get, higher fees for attacking American convoys. It's a risky business, and American troops want to keep it that way.