As soon as you enter Garbage you'll be given a new optional mission: Kill the bandit leader. This mission is given by Sidorovich and it ties in with two other optional missions you'll come across very shortly (Repond to the call for help and Repel the bandit raid).
Just ahead of you, you'll see a truck and behind that a collection of people. This is a bunch of bandits who are holding a loner, called Yurik, hostage. You can try to free him by killing all the bandits but they are very likely going to kill the loner... it is possible to rescue him, but it can be tricky.
Once the bandits are dead you'll be given another new mission. Bes, the leader of a small group of stalkers, is asking for help to defeat a group of bandits; this is the Respond to the call of help mission. If you managed to save Yurik he'll run off to Bes' camp at the vehicle scrapyard.
When you talk to Bes he'll inform you that bandits are trying to take over Garbage. Bes and his group had a run-in earlier and now he expects them to come back; he wants you to help them kill the bandits. If you accept you'll complete the Repond to the call for help mission and be given Repel the bandit raid mission.
Just before, or just after, you talk to Bes you way want to have a look inside the small building nearby - it has three metal boxes in it that contain some ammunition, bandages and possibly a medkit or two. Near the building is a tall tower with a broken ladder. On top of the tower you should be able to see one or two wooden crates - shoot them and you'll see a wonderful "rain" of ammunition - about 1000 9x19 mm PB1s rounds that are used by eg. the Viper 5 SMG.
Soon after you have accepted the mission from Bes you'll notice a stalker running towards you. He'll inform Bes that the bandits are approaching. The following part can be a bit tricky since you are going up against about 8 bandits and their leader (who is the one required to kill in the Kill the bandit leader mission). Bes and his men, however, will aid you so the odds are a bit more even. Please notice that for you to complete the mission all the bandits must be killed and Bes must survive. If Bes is killed during the attack, the mission will fail.
As soon as you've spoken to Bes you should move into position. The bandits will be approaching from the west, on the other side of the scrapyard. I have found that using the worn trailer (see screenshot on the right) for cover, and starting your counterattack by tossing a grenade or two at the bandits, works quite well. Once you have thinned their group you can move closer and finish off the rest. Once you have killed all the bandits the mission will be updated and you'll be prompted to talk to Bes.
Bes will reward you with 2000 RU and the mission will be completed. He can tell you a bit about Garbage and himself but nothing really important as such. You'll need to head back to Sidorovich in Cordon to get your reward for (and complete) the Kill the bandit leader mission. You can do that before you move on, should you choose, but you should able to meet Seriy, complete the missions at Agroprom and return to Sidorovich in due time. If you return to Sidorovich he'll give you an Akm 74/2U (with a loaded clip) and 150 rounds of 5.45x39 mm BP rounds. If you're going to sell the Akm be sure to unload it first to retrieve the (still rare) 5.45x39 mm rounds.
The camp at the vehicle scrapyard is often attacked by bandits, and you may even be attacked by more bandits right after you completed the Repel the bandit raid mission. If Bes should happen to be killed this time be sure to check out his body (and around him) since he's carrying a unique rifle - the Akm 74/2U Special which is basically an Akm 74/2U with an integrated silencer. Since you're at the right place you may wish to pick up another silencer if you'd like; refer to this page for the instructions on how to obtain it.
It's time to get to Seriy and get the information from him. As you get closer to the central hangar (to the north from the scrapyard) in Garbage you'll get a transmission from him saying that they're under attack by bandits and they could use all the help they can get. Ok, it seems like you once again have to step up to the plate. As you get closer to the hangar you're likely to hear alot of gunfire.
Inside the hangar you'll find Seriy and some stalkers engaged in combat with bandits. Help them kill the bandits and Seriy will call you over for a chat. When you talk to him he'll give you 2500 RU as thanks for the help, and tell you that a friend of his, called Mole, supposedly found a stash belonging to Strelok. The Meet with Seriy mission will be completed and you'll receive a new one: Get information about Strelok.
There is a nearby train car, and another one closer to the gate towards the west - the first one has some crates and a metal box inside, be sure to break them for some goodies. In the second train car you can find some ammunition and a Bandit Jacket.
You need to find Mole - fortunately he's located in the Agroprom Research Institute area, the same place where you need to find the military documents. Before you move on, take your time to stash surplus equipment away in the blue box inside the hangar. The missions in Agroprom Research Institute will yield alot of loot so be sure to only bring along the utmost necessary equipment. Since you'll mainly face enemies wielding Akm 74/2 rifles, bringing along only your Akm 74/2U may be viable, but having a shotgun for close encounters can still be a good idea.
When you are ready to move on, go through the hangar towards the west where the bandits attacked from. You'll notice a wall on the far side; beyond that is a bandit strongpoint which - surprise, surprise - usually has alot of bandits near it, so be careful when you approach. Even though you killed all the attacking bandits it doesn't mean that there still aren't bandits ahead.
Before you move past the bandit strongpoint you may take the time to pick up a special item - the Viper 5 9x18, a unique Viper 5 that has been reworked to use regular pistol ammunition (9x18 mm). You can find this unique weapon (and some other goodies) on the body of a dead stalker at the end of the tunnel - but beware, the tunnel is filled with Springboard anomalies.