Rust Commons is the second area group in the game which is after you leave Fyrestone, there are 60 missions that you will need to complete for this achievement.
There are missions in various areas:
• New Haven (Scooter, Helena Pierce, Marcus and Bounty Board)
• Trash Coast
• Earl's Scrapyard (Earl)
• Middle of Nowhere Outpost (Rust Commons East - Bounty Board)
• Claptrap Rescues (New Haven, Tetanus Warren, Scrapyard, Krom's Canyon, Old Haven, Trash Coast)
The missions in an order you might follow are:
• Claptrap Rescue: New Haven *
• Claptrap Rescue: Tetanus Warren *
• Corrosive Crystal Harvest
• King Tossing
• Is T.K. O.K.?
• Like A Moth To Flame
• Power To The People
• Up To Our Ears
• Scooter's Used Car Parts
• Hidden Journal: Rust Commons West
• Scavenger: Submachine Gun
• Firepower: All Sales Are Final
• Firepower: Market Correction
• Firepower: Plight Of The Middleman
• Jack's Other Eye
• Seek Out Tannis
• Meet "Crazy" Earl
• Claptrap Rescue: Scrapyard *
• Get Off My Lawn!
• Today's Lesson: High Explosives
• Hair Of The Dog
• Claptrap Rescue: Krom's Canyon *
• Earl Needs Food Badly
• Missing Persons
• Two Wrongs Make A Right
• Middle Of Nowhere No More: Investigate
• Middle Of Nowhere No More: Fuses? Really?
• Middle Of Nowhere No More: Small Favor
• Middle Of Nowhere No More: Scoot On Back
• Scavenger: Shotgun
• Scavenger : Machine Gun
• Altar Ego: Burning Heresy
• Circle Of Slaughter: Meat And Greet
• Circle Of Slaughter: Round 1
• Circle Of Slaughter: Round 2
• Circle Of Slaughter: Final Round
• Hidden Journal: Rust Commons East
• The Next Piece
• Altar Ego: The New Religion
• Altar Ego: Godless Monsters
• A Bug Problem
• Relight The Beacons
• Green Thumb
• Smoke Signals: Investigate Old Haven
• Smoke Signals: Shut Them Down
• Claptrap Rescue: Old Haven *
• Bandit Treasure: Three Corpses. Three Keys.
• Bandit Treasure: X Marks The Spot
• Jaynistown: Spread The Word
• Jaynistown: Getting What's Coming To You
• I've Got A Sinking Feeling
• Wanted: Fresh Fish
• Jaynistown: Unintended Consequences
• Jaynistown: Cleaning Up Your Mess
• Bait And Switch
• Claptrap Rescue: Trash Coast *
• Earl's Best Friend
• House Hunting
• Another Piece Of The Puzzle
• Not Without My Claptrap
All the missions at the various places are not available straight away, Clap Trap will tell you when the various places have new missions, once you have completed all of these the achievement will be yours