After completing either Coruscant or Dromund Kaas Nar Shaddaa will be the second planet players experience while leveling up. It's another city planet which means it pretty much sucks. Luckily for you, using this guide will make it suck just a little bit less. What level you come to Nar Shaddaa depends on what level you finished Taris and if you did the Bonus Series. Don't worry if you skipped the Bonus Series... Trust me when I say that most people do.
Anyway, let's get started with Nar Shaddaa. The very first quest you will pick up upon ariving on the planet will be from Minister Plennid...
When Diplomacy Fails
Recover 5 Republic Security Passcodes
For this quest you need to kill the Kintan Kings NPCs for the passcodes. They can be a rather uncommon drop so you may have to kill quite a few. This doesn't really matter though, considering the bonus quest has you kill 30 of them to complete it. You'll want to stick around for this bonus quest, it's a nice boost in XP especially if you skipped out on the Taris Bonus Series.
After you finish When Diplomacy Fails you'll want to head far west to get to the Taxi Terminal. Grab the Taxi path and fly to the Upper Promenade where the quest When Diplomacy Fails tells you to go. When you land grab the Quick Travel terminal thingy and head north to turn in your quest. After doing so, if you have a class quest in lower promenade do that before you continue to the Nikto Sector.
Once you arrive in the Nikto Sector you will want to grab the quest from Yeddu called "One Fell Swoop". Once you have that head east into the Nikto Sector and start by doing Armed and Dangerous.
Armed and Dangerous
Recover 4 Stolen Combat Implants
All over the Wannshock Tenements area (the first area you come to in the Nikto Sector) you will find glowing blue crates. Open them up and collect the Stolen Combat Implants. After you've gotten all 4 of them turn the quest in to Nurkolas up north. Doing so will start another quest called Slave Raiding. Also in the room right next to Nurkolas' there is another quest which is a Heroic +2 quest called Blood Money. If you're a healer or a tank with a healer companion you can probably solo this quest. It'll give some good XP so it's worth a try.
One Fell Swoop
Disable 6 Kintan Kings' Swoop Bikes
The Swoop bikes you will be getting to in a bit, but the second you start killing mobs out in the Wannshock Tenements area you'll get the bonus quest for this. The first step is to kill 16 of the Kintan Kings which you will find all over the place. The second step is to destroy 8 Fuel Cells which can be found in the same area as the Swoop Bikes. After you complete the Fuel Cells step do the Slave Raiding quest before doing the final step of One Fell Swoop's Bonus Quest.
Free 4 Kidnapped Republic Citizens
For this quest you will need to take the elevator to Fate's Hand Casino. The Elevator is located in the northern Nikto Sector. Once you make it to the Casino you'll want to free 4 Republic Citizens. They're in cages all around the Casino. Also while you're here be sure to do the Bonus quest, all you have to do is kill 18 of the Kintan Kings inside the Casino. After freeing the Republic Citizens your quest will update and have you shut off the Slaver Control Console in the northeast portion of the casino.
After you leave the Casino before you do another quest, keep in mind that this is a perfect time to grab the Nar Shaddaa Aim Datacron.
[Bonus Mission] Cripple the Kings
Kill the Kintan Ringleader for the Kintan Kings Medallion
You can find the Kintan Ringleader in southern Nikto Sector. He is marked on your map so you shouldn't have any difficulty when it comes to finding him. After you've killed him do your class quest.
Whatever your class quest is for here do that after you finish all of the regular quests.
Strike the Mountain Asunder
Find the Mountain
To start your "hunt" for The Mountain you will be taking the Kintan Arena Elevator in southern Nikto Sector to the Kintan Arena. Keep following the green arrow where ever it takes you while killing all the Kintan as you go. The bonus quest for here is to destroy the Weapon Cabinets in the northeastern section of the Kintan Arena. They're on the very first level. It doesn't matter if you do or don't do this bonus so I won't really go into that much elaboration about it.
Follow the green arrows until you run into The Mountain, once you do kill him and use the terminal behind him.
After doing that you have two options, if you've done all of the quests you can Quick Travel out of here or you can run out manually. The choice is yours. However once you've made the choice be sure to turn in every quest you have completed (including your class quests, we're at the point where almost everyone gets a new companion). After you've turned in all of your quests and you have the new series of quests (Waylaid + your class quest) you will want to head over to the Red Light Sector. Once you're here speak to Ilox and turn in Waylaid and accept Shore Leave.
On your way north through the Red Light Sector you'll come across Chief Rarkgah who will give you the quest "Back Alley". Further north of Rarkgah you'll find Malahan and a terminal near him. Malahan gives the quest "Cleansing the Spice Trade" and the terminal gives a heroic +2 quest. So you have the option of completely ignoring that if you choose. First up, let's do Shore Leave.
Investigate Club Ufora
Rather easy quest to do, just run through the club following the green mission arrow. The bonus mission for this quest is almost impossible not to do since the Bouncers are all in your way. After you finish Shore Leave you'll want to continue west and do the next quests...
Cleansing The Spice Trade
Just destroy the East/West labs for now
Activate a turret and hold off the bleeder forces
For this quest you're required to activate a turret in the Red Light Sector - Back Alley Slums area and hold off all the Bleeder Forces which come at you. It's easy to do, just be warned that you get over run with mobs while doing it. The first bonus quest you get is to kill 20 Bleeder Forces, which you can do easily. The second requires you to destroy 5 Bleeder Shipments. We'll get to that later, for now just kill the 20 Bleeder Forces. After you've completed the quest it will update with another one requiring you to kill a bunch of named mobs. We'll get to this part later.
[Bonus Quest] Bled Dry
Destroy 5 Bleeder Shipments
In the far northern end of the Red Light District you will find glowing blue crates. Destroy 5 of them to complete this quest. This quest will update and you'll need to wait until later to do Stage 3.
Investigate the Quarantine Zone
In the far northern end of the Red Light District you'll see the Quarantine Zone Elevator. Take this Elevator down to enter the Quarantine zone. Follow the green quest arrow throughout this area and kill any Lab Security that get in your way for the bonus quest.
At some point in time whenever you pass your Class Quest you'll want to do it.
Defeat Beauty Queen, "Guns", Oilcan, and the Rip
Now it's time to start doing this quest again. However, this time around you're going to be required to kill a bunch of named NPCs. You'll want to kill them along your route as your doing the other quests here.
Before going too "deep" into the eastern end of the Red Light Sector, you may want to grab the Presence Datacron!
Cleansing The Spice Trade
For this quest you will want to destroy the final two labs that you need to destroy as well as kill the remaining 25 Spice Workers that you have to kill for the bonus quest.
[Bonus Mission] Bled Dry - Stage 3
Sabotage 3 Speeder Vehicles
You will find the speeder vehicles all over the northeastern section of the Red Light Sector. Sabotage 3 of them to get an updated quest with the final stage.
[Bonus Mission] Bled Dry - Final Stage
Retrieve a Vial of Bleeder Blood from the Bleeder Street Captain
The location of where the captain is can be found on the map. He is a level 21 elite. Kill him, loot the blood and you're done!
This should complete all of the quests for the Red Light Sector. Turn in everything you can and accept all the new quests. Also if for some reason you haven't finished your class quest do so before turning in any quests. After you've done that you should have your class quest and one additional quest which will both point you to the Industrial Sector. So hop on a Taxi and head on out there! On your way down into the Industrial Sector area you'll come across a lounging Hutt who has a quest for you. The terminal next to him has a quest too but it is a Heroic +4 so I ignored it.
Now let's get started!
This Datacron is out of the way, but, this is when you will be the closest to getting the Cunning Datacron. Up to you if you want to go out of your way to get it.
Retrieve an Access Card
For this quest you have to kill the Security Lieutenants and collect an Access Card. Once you have the Access Card you will need to access a Security Terminal. After you do that you will need to shutdown the data intake process at the terminal in the far western end of the room. Once that's done you have to activate the data-miner (It's all a pain in the ass I know). After you activate the data-miner you will need to set the Transmission location and then trigger a data wipe. Finally you're done.
The bonus quest has multiple stages starting with the first that requires you to kill 10 BetterLife personel. After you complete the first stage you will unlock stage 2 which you will have to destroy 5 Betterlife Technology. The Betterlife Technology nodes are computer terminals which can be found all over the area destroying one will give you credit. After you complete Stage 2 you will need to kill the Betterlife Security Chief in the center of the Betterlife area and collect his formula.
Return to the Hutt and turn in your quests, accepting the next one in the process.
Destroy the 10 Imperial Lab Equipment
Rather easy quest, you'll find the equipment around where it shows the mission objective on the map. They are small terminals and they glow blue. You can't miss them. Also you can destroy the cryo-chamber looking things in the large room. The bonus quest here is easy too, all you have to do is kill 20 Imperials for it.
Once you're done this quest you will want to head on over to the next one in line which I've found to normally be your class quest.
Do this now before moving on to Genocide.
Speak to Ganuk
Talk to Ganuk and turn in your quest and accept the next one that he has called "Chemical Agent".
Install the scanner into the mainframe
A really easy quest, all that is required is for you to kill your way far west and, well, complete the mission objective! Kill all of the Imperials you see on the way there so you can complete the kill 15 Imperials Bonus Objective. After you do both of these quests and access the terminal you'll get a new quest called "Extermination"
Infiltrate the Pharmalux Waste Processing
Your two quests once inside will be to pretty much kill everything in sight. So... Kill everything in sight making sure you follow the quest objectives as you go. After you finish the quest leave this area and return to that big fatty hutt in the Lower Industrial Sector.
After you've turned in that quest it is time for us to be leaving the Lower Industrial Sector. At this point in time usually there is a class quest for you to complete and you probably dinged throughout the Lower Industrial Sector so you'll want to train as well. Before moving on to Shadow Town, which is the final area of Nar Shaddaa be sure to do your class quest and have it updated enough so the next part is part of Shadow Town. Once you're in Shadow Town you will want to do the quest "Those Left Behind".
Nar Shaddaa Leveling Guide - Shadow Town
Those Left Behind
Talk to Zan Loren
Head over to where Zan Loren is at marked on the map and talk to him. Turn in the quest you have for him and accept the next one that he gives you called "Access". Also in the same room as Zan Loren you'll notice a terminal that has a quest available at it as well, it's a Heroic +2 quest though so ignore it if you don't think you got what it takes to do it.
Retrieve the 3 Security Codes
For this quest as well as the Bonus Quest you will need to kill the inhabitants of Shadow Town. For the Security Codes you will need to kill the Wardens. Depending on what prefix the warden has determines what security key he drops. For example the Security Warden drops the Security Access Code and the Subsystem Warden drops the Subsystem Code. The Chief Warden drops the other code. Once you have all three codes return to Zan Loren.
Turn in "Access" and accept "A Tough Sell".
A Tough Sell
Speak with Kesler
For this quest you need to go far to the south in Shadow Town and speak with Kesler down there. After speaking with Kesler down here to update your quest head west.
A Tough Sell
Recover the Modified Cred Stick
Kill all of the Imperials in the area down here on your way to Access. One will be sure to drop the Cred stick you need and also you'll complete the Bonus Quest by a longshot.
Use the Security Console
Another rather straight forward quest. All you have to do is use the Security Console and you're done the quest. However there will be another quest you will acquire right after turning this one in.
This is also a great time to collect the Nar Shaddaa Strength Datacron!
Search for Ako Domi
This quest is really easy, and really straight forward. There is no reason to waste your time making you read a guide for it. Just do it and the bonus before returning to Kesler and turning in.
Now is the perfect time to do your class quest before returning to the SIS base and turning in your quests.
After you've finished your class quest you will want to return to the SIS base and turn in the other two quests you have to turn in. After doing that you will be done all of the quests on Nar Shaddaa (excluding the Bonus Series of course). All that's left is your Class Quest, whatever is left of it that is. So, do your Class Quest and then it's off to Tatooine!