Once you wake up, you are free to move around, and will be given a quick overview of the controls as needed to go through the rubble.
There is only one path through the cave, which requires crouching under obstacles, jumping into a vent, and going prone to crawl under a beam. Eventually, you should reach a ladder that you will climb up.
When you see a short cutscene, this is the first point where you can get injured. While you can run past the enemy, the best method is to throw a rock through the upper cave hole to distract the guard, then run past. When you reach the doorway, the cavern behind you collapses; continue until you reach and open a door.
The radio you collect there puts you in contact with Doyle, who will assist you by describing what you will need to do next. After his introduction, pickup the pistol and ammo (on the crate and shelves), the grenade, and the body armor (at the back exit).
The huts will have a few items, and will be your first encounter with mercenaries. The first hut will contain a machete, which can be used for a silent kill. The second hut contains a medikit, and the third contains an M4 assault rifle.
When you clear the huts, you will be alerted to an objective on the compass to the left. This leads you to binoculars, which can be used to see for a far distance, amplify sounds, and to "tag" enemies to make them appear on the radar.
After the binoculars, you will be directed to an enemy camp to the west, and will need to steal a vehicle. You can choose for an aggressive or stealthy approach, but in either case, a mercenary will try to sound an alarm if you get spotted. There is also a helicopter that may detect you, causing mercenaries to become alert as well.
If you want, you can open the explosives section by collecting a keycard in the headquarters (located on the right), and going into the other building.
The buggy is located at the back of the base, behind the headquarters. There is also extra body armor and binoculars. Ride the jeep and take a left turn to follow the path, and shoreline. If you have to abandon the buggy, there are extra vehicles that you can use or obtain simply by killing the soldiers using or guarding them.
When you reach the large sandy section, you will encounter two vehicles. Quickly drive past them to avoid being damaged by a rocket attack. Continue left and past the crashed plane until you see the carrier.
The carrierhas guards on the front, as well as a few partol boats nearby. Enemies can still attack and injure you while underwater, although swimming may make you harder to see. Approach the carrier's bow to reach a hole that will take you to the next level.