Stay hidden behind the storage box where you begin.
Wait for the nearest man to move away from the others.
Once he turns yellow in Survival Instinct view, meaning he's out of sight of the others, kill him with a silent headshot.
Then take out the guy on the ledge above. Don't let him see you, since he'll alert the others and start shooting down at you. If he turns toward you, release LT/Right Mouse to stow your bow and duck behind cover (as shown in the first screenshot above). If he moves off to the right, shoot an arrow into the wall at the left end of the ledge.
He should move toward the source of the sound. Then you can shoot him while he's staring at the wall like a moron.
If you have poison arrows, wait for the 2 guys standing in the middle of the room to go investigate the fuel leak.
Then kill them both at once with a single poisoned arrow. (If you don't have poison arrows, save these two for last. Try to get one with a headshot, then kill the other one quickly before he can retaliate.)
Apart from the guy writhing on the floor in agony, there is one more man off to the right near the computers. Try to kill him with another headshot while his back is turned.
Even if he notices you, it's no problem as long as he's the last man alive. Just shoot him with bow or pistol as he approaches.
It's up to you whether or not to kill the maimed lieutenant. You'll get a little XP if you do.
Take a quick spin around the room to loot the bodies and pick up pistol ammo (near the computers and on each of the side ledges) and cloth (in a container to the right of the computers).
Pick up a lantern, stand well back from the roll-down door, and lob the lantern into the puddle of fuel.
The resulting explosion blows open the garage door, alerting 2 more men outside.
One of them runs in immediately. Switch to your pistol (D-Pad Down) and shoot him as he approaches.
The other lurks outside behind some boxes. Peer out the door and shoot the red fuel barrel behind him. (If necessary click the left stick or press Shift on the keyboard to Shoulder Swap; i.e., change the direction in which Lara leans while aiming. This will help you shoot more effectively from cover.)
That should do the trick.
If you hesitate, he will start throwing explosives toward you. Watch for the red warning icon and dodge out of the way to avoid injury.
Out in the driveway, gather herbs and hardwood, and examine the mural (3/12), Night Work from the Soviet Crests set, for XP and Russian language skill. If you've been thorough, this should allow Lara to advance to Level 2 Russian. Then climb through the opening where the metal wall meets the side of the building.