The 'Bridge Overlook' camp is just ahead. As soon as you move over the bridge, quickly wiggle the left analog stick to the left/right, then press Y or Triangle to correctly perform the quick time event. More enemies will be moving in shortly, so hide behind the low wall and start taking them out one by one. You can find some [RIFLE AMMO] here to replenish your supply.
As you proceed, more enemies drop from the building to your right. Backtrack to take out the ones with axes and swords, then dispatch the rest of them who are still on this building. As you head around the corner, still more enemies appear, especially inside the large building up ahead. Quickly aim at the red explosive barrels on the first floor to waste all of them at once. The next wave of enemies appears as you approach this large building. Take cover and dispatch them one by one.
All collectibles in the Base Exterior area.
Now's a good time to collect some items we skipped in the heat of battle:
• Backtrack all the way to the bridge and search behind the truck to find a [GPS CACHE].
• Next to the first building you can find [HANDGUN AMMO] and [RIFLE AMMO].
• [RELIC - #1 SENSHI ELITE (JAPANESE DOGTAGS)] can be found by climbing this building (scramble up the wall on the left side).
• [DOCUMENT - #4 DIARIES OF A MADMAN (THE SOLARI)] is found on the first floor of the large concrete building you blew up by shooting the explosive barrels. You can also find an [XP BOX] nearby, on the same floor. The second floor cannot be reached.
Scramble up the wall to the west of this building to encounter the next wave of enemies. Whatever you do, don't drop down until you've killed all enemies, including the two molotov cocktail-throwing bastards in the building across the street, who like to hide a lot. After dispatching them all, drop down to encounter a new, tougher enemy type: A guard with a riot shield.
While he may appear to be nearly invincible, it's actually incredibly easy to defeat him once you learn to adequately dodge. Whenever he want to hit you with his machete, press B (or Circle) and move right at the same time, then immediately aim and fire at him while his body is exposed. Do this several times to defeat him. It's easier if you're already aiming at him, sidestep to the right, then empty a few bullets of your rifle into him. One other enemy needs to be dispatched after this, but that shouldn't be much of a problem. Looting the sub-boss will probably yield [BOW PARTS 1/2].
Search the area for [RIFLE AMMO x3] and [ARROWS], as well as a [PLANT] in the southwest corner, then go inside the building. To your immediate right you can find [RIFLE AMMO x2] near the burning barrel, and there's also a [SALVAGE LOCKER] inside this small room that you can crack open. Upstairs you'll find [SALVAGE] and a [SALVAGE BAG] (there's a burning barrel outside on the same floor). [RELIC - #2 SENSHI ELITE (MARKSMANSHIP BADGE)] can be found by cracking the closed door open; it's on some boxes in the room behind it.
Head upstairs to discover the 'Radio Tower' base camp. Inspect the carpet lying next to this camp to find [DOCUMENT - #3 DIARIES OF A MADMAN (RESEARCH)]. Slide down the rope to reach a previously inaccessible platform that contains [RIFLE AMMO], and [XP BOX], and the [TREASURE MAP] of the area.
Climb the rope to the west to reach the radio tower. 'Simply' climb it all the way to the top to trigger a scene. You'll then have to tune the radio. Move the left analog stick to the fourth marker / and then switch tuner (you should hear a voice through static). Move the left analog stick once again in clockwise fashion until you hear a clear voice, then broadcast your message. [100 XP].
Slide down the rope, then approach the fuel tanks and turn the valve. You can find some [RIFLE AMMO] near the corpse across the fuel tanks, and some more [RIFLE AMMO] inside the building. You'll also find the handy [FIRE STRIKER] on the table, which allows Lara to light her torch anytime she wants. (It does not grant burning arrows; you'll need some other gear for that, since Lara cannot wield her torch and bow effectively at the same time.)
: You can hunt rats here to gain some extra XP.
Set fire to the tanks to trigger a cutscene and a 'chase' sequence. [400 XP]. You'll have to slide Lara down safely without hitting the sharp obstacles along the way. At the end, get a good grip, quickly climb up, then immediately jump to the walkway to the right. [100 XP].