Once you reach the Lower City, you will see a gang fight between Black Vulkars and Hidden Beks. The Vulkars will win, and then turn on you. Dispatch them and explore the apartments. You'll want to avoid the main entrance to the Vulkar base, for now, and head in the direction of Javyar's Cantina and the Hidden Bek base.

Lower City

1. To Upper City
2. Black Vulkar base main entrance. You can't get through here, you have to enter this base by another route.
3. Lower City Apartments #1
4. Javyar's Cantina.
5. Hidden Bek base.
6. Lower City Apartments #2
7. To Undercity. You'll need papers to get past the guard. You can get these papers by making a deal with Gadon of the Hidden Beks.

Lower City Apartments #1

1. To Lower City
2. Repair a disabled security droid here and set it in patrol mode and it will roam the halls, taking out Vulkar thugs. You get XP for repairing the droid, so you don't really lose anything.
3. Various Vulkar thugs inhabit these apartments. Dispose of them and loot their footlockers.
4. Vulkar gang boss and enforcer. A bit tougher, but with nicer loot.
5. Twisted Rancor Trio's apartment. To open the footlocker, read the history of the band located in the nearby desk. Then activate the holograms in the order of the members joining the band. In case you don't want to do the hard work, it is: Elinda, Ujaa, Ujii, Loopa, Fodo, Ashandi. The crate contains Echani Fiber Armor, which is not only decent by itself, it's upgradeable.
6. Matrik's apartment. He has a bounty on his head and a scheme to fake his own death. Give him the permacrete detonator you purchased at Kebla's shop (you did purchase it, right?) and he'll fake his own death. You can later collect the bounty for him by lying that you killed him. You get Light Side points for helping him escape (and no Dark Side points for lying to collect the bounty).

Javyar's Cantina

When you first enter the center of the cantina, you get to witness Calo Nord in action. He's not talkative and not killable by you at this stage of the game. You'll also meet Mission Vao and Zaalbar here.

1. Exit to Lower City
2. Bounty office. Talk to Zax the Hutt to get the bounties. For Light Side points and XP, you can collect on Matrik by helping him fake his death and then lying to Zax. You can pay off Largo's loan, and bribe Holdan to cancel the bounty on Dia. You can also collect the bounty (by killing) on Selven. You can only collect the bounty on Bendak Starkiller by playing your way through the dueling arena and then engaging Bendak in an illegal deathmatch, which will earn you Dark Side points. In one corner of this room, Bib Surool is auditioning a dancer. For a little fun and XP you can help the dancer with her audition.
3. Holdan hangs out here. Unless you have a high enough Persuade skill, it will cost you 200 credits to get Dia's bounty removed.

Hidden Bek Base

Unless you choose, later, to betray Gadon Thek and the Hidden Beks, most of their base is off-limits to you. Just walk into the main room and find Gadon along the back (North) wall. He'll explain Bastila has been captured by the Vulkars, put up as the prize for an upcoming swoop bike race, and you need to win that race to free Bastila. You can ensure your win by recovering a prototype swoop bike accelerator from the Vulkar base. The only way into the base is through the sewers, and the only person who knows how to use this entrance is Mission Vao and she's wandering around Undercity. Oh joy...

1. Exit to Lower City
2. Gadon Thek.

Lower City Apartments #2

The first time you enter these apartments, you'll see a scene in which bounty hunter Calo Nord offs some Rodians. You may have already met him in the cantina, but he's no more talkative here than he was there.

1. To Lower City
2. Vulkar gang boss. Watch out for a frag mine in the closet.
3. Miscellaneous Vulkars.
4. There's a mined, sealed chest in the corner. Disable the mine using Demolitions skill. To open the chest, you need to answer three questions. You can obtain the answers by reading the message on the answering machine in the desk. FTR, the answers are: Hyperdrive, uncle, Alderaan. Score some sweet Republic Mod Armor from the chest.
5. Selven's apartment. She's one of the subjects of the bounty hunt. She's actually guilty and your only choice is to collect the bounty (assuming you've taken the bounty hunt quest). There are no Dark Side points for killing her.