How to unlock: You need to complete mission Club 27 in Bangkok.
Comment: You will unlock the achievement, regardless of the methods you choose to assassinate Jordan Cross and Ken Morgan.
Drop the Bass
How to unlock: kill Jordan Cross and Ken Morgan with a falling coconut.
Comment: this is one of the most difficult achievements in the game. It requires you to make sure that both targets appear in the hotel lobby. You can accomplish that by stealing the identity of a pest control technician and meeting with the manager of the hotel. Wait for Jordan Cross AND Ken Morgan to reach the lobby. Now put the insecticide in the ventilation system (M6.10).
Jordan Cross, Ken Morgan and other guests in the lobby should lose their consciousness. Get to the lobby as soon as possible and drag one of the bodies by the palm tree. Now shoot down one of the coconuts, to make it fall down and kill your target. Repeat the sequence with the other target. You will trigger an alarm, so just kill all the guards in sight (they may try to revive the people). Don't worry about your score at the end of the mission, and purely focus on unlocking the achievement.
Elephants Never Forget
How to unlock: Destroy all gold elephant statues in the hotel and leave the building.
Comment: There are 18 statues marked on your map, and all of them are located in a luxurious apartment in the south part of the hotel on level 4. You can kill all the people in the apartment or take your shots from a hidden place (use a silencer) while using a security uniform. Information on the exact location of the statues, is provided below. Keep in mind that you are after the golden statues, so ignore the silver ones. Each destroyed statue will result in a short sound sequence.
Statues 1-3: south-east part of the apartment.
Statues 4-6: south part of the apartment.
Statues 7-8: south-west part of the apartment.
Statues 9-10: a room in the south-west corner of the apartment.
Statue 11: north-west part of the apartment.
Statue 12: north part of the apartment. There are three silver statues that you should ignore.
Statues 13-15: north-west part of the apartment.
Statues 16-18: Reach the higher level of the apartment (level 5) and investigate one of the rooms in the west.
Destroy all the statues and get to the roof (the one with a glass piece) or leave the building.
How to unlock: You need to use all the opportunities available in Bangkok.
Comment: Use all the opportunities to eliminate your targets. You can go through their list by pausing your game and selecting the right tab. It is obvious that you cannot complete all of them in a single gameplay. You need to play Bangkok several times and each time you should focus on one specific opportunity (maybe two if they are related to different targets and do not exclude one another). Tips on how to eliminate main targets were presented in the walkthrough.
How to unlock: Complete the fifth level of escalation in Bangkok.
Comment: With each escalation, Agent 47 will face more and more complex challenges related to assassinations. Bangkok offers several escalations, and in order to unlock this achievement, you need to complete one of them.
Scouting for Talent
How to unlock: You need to select an alternative starting point in Bangkok and use the Agency to help you smuggle something to the area.
Comment: Both options will become available once you reach higher ranks. Try to complete Bangkok mission on "regular rules" at least once, before you decide to choose the starting point and use equipment delivery.
One Night in Bangkok
How to unlock: You need to reach the 20th rank in Bangkok.
Comment: You can advance to higher ranks by completing different challenges related to Bangkok mission. This includes eliminating main targets using various methods, finding unique items that may come in handy during assassinations, or beginning the mission in from different starting points. You don't have to complete all the available achievements to reach rank 20 (the game informs you on your progress after you complete a mission), so start with achievement that you find most interesting.