There is no real surefire way to obtain this achievement but what it entails is going flawless by winning all four rounds of a ranked match. This can be through killing the enemy team, playing the objective or allowing time to run out. My tip would be find a squad of people all with mic's so you can communicate. Also in ranked you get to select your rooms so think of the best one to defend. You should have a mute, rook, and possibly a castle when on defence. Use mute to prevent thermite from breaching walls, rook to give that extra padding and castle to make reinforced barriers. Always reinforce the drop hatches and stay separate but close, as in if one person goes down they won't be able to kill another.
For attackers make sure you find the location, if possible set up your drones in a position that can be useful for spotting enemies, take it slow and check about. It is unlikely that the enemy will all camp the objective, they generally disperse and try to stop entry to the building. Our squad tended to run blitz, thermite, sledge, ash, and fuze. obviously be careful with fuze as he can team kill and kill hostages. Again take it slow and clear levels, also blow multiple charges at once and attack at more then one spot, this can confuse the enemy. People also get antsy in this game so they may come after you if you are patient. Even they aren't being used destroy the cameras just in case and with some luck you can bag yourself this achievement.
P.S Glaz is also a useful attacker depending on the map, enemies tend to watch out windows and try to pick people off so a sharpshooter glaz is a useful weapon.
If this doesn't seem like your cup of tea you could always get two groups of five and connect, let one squad win a flawless and then at the end of the game press x to rematch them and let the team that lost win the game. Hope these tips are of some use and happy hunting.