1. I would recommend getting the appropriate gear first.
   
2. Complete the Ilum story line: it was the original end of the story in 1.0. At the same time, look for a group for Karagga's Palace: it is the start of both the Rise of the Hutt Cartel story line and the Dread Masters storyline.
   

Also, if the BBA Bounty Contract Week event, "Life Day Event," Rakghouls Resurgence, or Relics of the Gree event comes around, participate in them: they are not here all the time.

Ilum / End of the original story:

1. Ilum Planetary Storyline - You get this quest ({Crystal Ball} or {First Strike}) automatically when completing Chapter 3. It is under the "Class" category on the "Mission" window.
   
2. The original PvP on Ilum took place during the Planetary Storyline (and possibly during the two Flashpoints)
   
3. Battle of Ilum (Flashpoint) - On Ilum after completing the Planetary Storyline
   
4. False Emperor (Flashpoint) - On Ilum after completing Battle of Ilum. Excellent end battle similar to Episode 3 and 6 end. My second favorite Flashpoint, after Directive 7.
   

Outbreak of the Rakgoul Plague:

1. Trouble in the Tion Hegemony / Outbreak in the Tion Hegemony: Besides starting on the main hub of the fleet, the mission to start this mission can be found on the Vanguard of the fleet -> Mission Deck -> Tion Hanger.
   
2. Kaon under Siege (Flashpoint) - Starts on the Vanguard of the fleet in the same place as the above after a conversation.
   
3. Lost Island (Flashpoint) - Toughest level 50 Flashpoint due to mechanics: extra gear helps, but expect to spend a longer time and die more than most Flashpoints. My third favorite Flashpoint. Starts on the Vanguard of the fleet in the same place as the above after completing Kaon under Siege.
    
   Rakgoul event was happening at the same time of these two flashpoints
    
   
4. Rakghoul Resurgence (event): Event that can be completed before level 50. It is mentioned that one of the main character's children died due to the Rakghoul plague during the original Rise of the Rakghouls event.
   

Rise of the Hutt Cartel:

1. Karagga's Palace (Operation) - Also part of the Dread Master's story
   
2. Makeb Storyline - Happens at the same time as the Macrobinocular storyline. Starts with the holoterminal on your ship.
   
3. Macrobinocular Storyline - Happens at the same time as Makeb. Level 52. Best done with the Macrobinocular, GSI Dailies, and HK-51 stories: they all take you to almost all of the planets hunting for objects.
   
4. Scum and Villany (Operation) - Not too sure about this one: I have not completed it. Is part of the Dread Master's story. Level 55.
   

Denova:

1. Novare Coast (Warzone)
   
2. Explosive Conflict (Operation) - Part of the Dread Master's story.
   

The Gree:

1. Republic Coruscant Side Missions during the Prologue
   
2. Chevin Grand Acquisition Race Event
   
3. Terror from Beyond (Operation) - Part of the Dread Master's story.
   
4. Ancient Hypergate (Warzone)
   
5. Relics of the Gree Event - Has to take place after False Emperor lore wise. Has no spoilers if you have participated in Ancient Hypergate. All characters level 50 and over are boosted to level 55 stats; however, companions are not.
   

Czera / CZ-198:

1. CZ-198 Dailies - New in 2.3. Mission starts on CZ-198, then takes you back to the fleet's Vanguard ship. Level 55.
   
2. Czerka Labs (Flashpoint) - Part of the CZ-198 dailies. Level 55.
   
3. Czerka Meltdown (Flashpoint) - Part of the CZ-198 dailies. Level 55.
   

Kuat

1. Kuat Driveyards - Currently scheduled to be release in February 2014. Can be completed at any level 15 and over.
   
2. Various Galactic Starfighter Maps above Kuat - Only available to subscribers and preferred players currently. No gear requirement. F2P get access in February 2014. Can be completed at any level.
   

1. Belsavis Imperial Planetary Story at the beginning of Chapter 3 - Starts on Belsavis Orbital Station.
   
2. Karraga's Palace (Operation)
   
3. Explosive Conflict (Operation)
   
4. Section X (Dailies) - Section X could happen any time between Explosive Conflict and Oricon. F2P need an unlock for this area.
   
5. HK-51 Quest - Starts on Section X and is part of Section X. Best done with the Macrobinocular, GSI Dailies, and HK-51 stories: they all take you to almost all of the planets hunting for objects. Costs 125k credits for one of the parts to complete. F2P need an unlock for starting and completing this quest: they can do the middle without an unlock.
   
6. Seeker Droid storyline - Similar to Section X: could happen any time between Explosive Conflict and Oricon. Starts on the fleet, or on the Capital World, or on Makeb (story is the same any way it is started.) Level 52. Best done with the Macrobinocular, GSI Dailies, and HK-51 stories: they all take you to almost all of the planets hunting for objects.
   
7. Terror From Beyond (Operation) - Level 55
   
8. Scum and Villany (Operation) - Level 55
   
9. Oricon (Dailies) - New in 2.4, Level 55, people are mentioning that this daily requires higher gear than most dailies as mentioned above.
   
10. Dread Fortress (Operation) - New in 2.4, Level 55, Requires higher gear than mentioned above: Black Market gear or above recommended.
    
11. Dread Palace (Operation) - New in 2.4, Level 55, Requires higher gear than mentioned above: Black Market gear or above recommended.
    

• Black Hole - For the Republic, its the news terminal on the fleet.
  
• Belsavis Bonus Series - Starts with just a terminal on the fleet: no voiceover cutscene
  
• Eternity Vault (Operation)
  
• Rest of the Warzones (could possibly happen any time, not just after Chapter 3)
  
• GSI Dailies: Obviously have to happen after you get the Macrobinoculars and Seeker Droid: they start with GSI contacting you through mail stating that they notice that you are in possession of a valuable Macrobinocular and Seeker Droid. Level 52; some missions require you to go to areas with level 55 enemies, but the enemies can be avoided.
  
• BBA Bounty Hunters Event (could possibly happen any time, not just after Chapter 3)
  
• "Life Day Event": Happens around Life Day (Star Wars' Christmas.): Could occur before Chapter 3: just involves throwing snowballs to get prizes.
  

• Datacron hunting: Use http://www.swtor-spy.com/datacrons/ to get permanent stat increases and codex entries about the history of Star Wars up to the start of the story.
  
• Uncover map areas: Go back to a planet you've been to and try to uncover the entire map. Best done with the above point.
  
• Kill World Bosses: Bosses that typically require a large group of players to take them down. Companions cannot fight them. Some of the early world bosses are abled to be soloed with a tank or healer. You can sell the items you get on the GTN for credits.
  
• Unique Champion / Unique Elite hunting: Some unique champions and elites give achievements for killing all of them on a planet. Typically, these champions and elites have proper names.
  
• Spy droid hunting: Requires Macrobinoculars. Hunt for certain probe droids and scan them with the Macrobinoculars
  
• Other Legacy Achievement hunting: Look up various achievements and try to complete them.
  
• Tauntaun hunting: On Hoth, you can get the (annoying) Tauntaun mount by purchasing lures and trying to lure Tauntauns back to their nest. Easier done with Macrobinoculars, since they will point you to the nests if you are close enough.
  
• GSI Speeder / Dreadseed / Star Forager Armor hunting: Use your seeker droid to hunt for special speeder parts and armor. http://dulfy.net/2013/04/15/swtor-dreadseed-and-star-forager-armor-locations-guide/
  
• Roleplaying: Get a group of people together and roleplay a story / meeting / night out / ect. Easier done on a RP (including RP-PvP) server.
  
• Open World PvP: Fight other players of about the same level on planets. Easier done on a PvP server.