Glitch Warning: This trophy is unattainable until you update the game to version 1.03 or higher! Reports confirmed the kills for XM-53-DF Rocket Launcher is not counted which prevents the Master of Arms Decoration to unlock and also some reports confirmed that completing all the accolades for all the missions will earn you the challenge but not the decoration. If you download version 1.03 or higher, you will have no problem obtaining this trophy.

In the Safehouse, you can see your Service Record which will display medals for great achievements. For this trophy, you must get all the medals. This is easier said than done as all of the medals have exceptionally difficult or lengthy tasks:

1. Master of Arms - Earn all Campaign Weapons, Attachments, and Camos.
Each gun has attachments and camos which can be obtained by killing enemies with that weapon. Each primary weapon has 4 camos, with the last one being unlocked after getting 650 kills with that weapon. By the time you get all the camos, you will have also got the attachments for it too. You will have to buy each gun aswell but you can use the video below to get enough Fabrication Kits to buy every gun.

2. Dedicated to Excellence - Fully upgrade all Cyber Cores.
Refer to  Unlocked Potential for more details.

3. Armament Superiority - Unlock and purchase all weapons, lethals, tacticals, and Cyber Combat Abilities.  
You can unlock weapons, lethals, tacticals, Cyber Combat Abilities etc. while leveling up your progress in campaign you should unlock them all naturally while replaying missions for other decorations and by completing challenges and accolades as you most certianly will have reached the max level of 20. After you unlock them you can purchase them in your Armory Section at the Safehouse using your Fabrication Kits, you will earn a lot of Fabrication Kits while leveling up and completing accolades and challenges, there is also a Secret Code will give you around 50 to 100 kits and this will help you to purchase everything, to perform this code you need to access your Data Vault at the Safehouse and highlight the spinning S on the left corner, then Hold down  +  and press  then , now type the code "MANIFEST" and you should earn your Fabrication Kits directly. Follow the video guide below to be sure for all the steps.
 

The Secret Code to Get Fabrication Kits

Credit to Knotty Dude for the video.

4. Heroic Service - Complete the Campaign on the Veteran difficulty setting.
If you follow the Roadmap and beat the Campaign on Realistic, you will get this decoration too. Refer to  No One Will Believe You for tips on this difficulty

​5. Legendary Service - Complete the Campaign on the Realistic difficulty setting.
If you follow the Roadmap, you will get this Decoration after completing the final mission. Refer to  No One Will Believe You for tips on this difficulty

6. Immortal Fame - Complete every mission in the game at least once on Veteran without restarting from a checkpoint.
To earn this decoration you need to complete all the mission on Veteran difficulty without restarting from a checkpoint, you can complete this decoration solo or in co-op, if you need some partners, be sure to create or join a Gaming Session. If you downed while playing in co-op and your partner revive you, it will not have an effect the trophy as you didn't restart from a checkpoint. For some tips and strategies refer to the same tips in  No One Will Believe You.

7. Chronicler - Locate all of the Collectibles in the Campaign.
Refer to  Curator for the locations of all the collectibles.

8. Above and Beyond - Complete all Accolades for all Missions.
Accolades are challenges for each campaign mission, you will have around 15 to 17 accolades in each mission for a total of 176 Accolades. Each Accolade requires a specific task to earn it. You can check every mission's accolades at the Safehouse in the mission select section. Once you complete the game it will be the best time to clean up any unearned Accolades, you will find out that there are some Accolades required specific kills in certain points and some want you to get a high score in a mission. You don't have to complete the entire mission to save any recently earned accolades, instead of that you can just quit to the main menu when you complete any Accolades and the game will auto-save your progress, also when you die after completing the Accolade your progress will be saved. Here are some tips on Accolades in general:

1. Accolades can be checked and the progress for some can be tracked during a mission by checking the Accolades menu upon pausing the game.
2. Once a challenge is completed, it will stay that way even if you die, restart or quit the mission. However, if you made partial progress to a challenge and died, your progress will be reset to what it was at during your last checkpoint. For example, the "Clear Skies" accolade in the first mission requires you to shoot down 4 VTOLs with a mounted turret. If you passed a checkpoint with 1 VTOL kill then got two more and died, it will be reset back to 1 instead of kept at 3.
3. Be sure to carry a grenade in case to mess up an area specific accolade. That way you can kill yourself and restart from an earlier checkpoint as there is no option (yet) to restart from the last checkpoint. Be sure to remember the above tip when doing so.

  There is a video playlist for all the locations of the Accolades in the game with a guide to complete each one:
Call of Duty:Black Ops III - All Accolades Location + Guide For How To Earn Them All
Credit to NonstopTrophies for the Videos

9. Grim Reaper - Neutralize 2,000 hostiles.
This decoration will come naturally while going for other decorations, you need to get 2,000 kills in campaign to earn it.

10. Duty Calls - Complete all Campaign Challenges.
There are 33 Challenges for the campaign and you can at any time check your challenge progress by opening the main menu, selecting challenges, and then choosing campaign. Most of them aren't too difficult but are time consuming, usually involving using certian Cyber Cores to kill enemies.

Unlike Accolades which are level specific, challenge progress can be made in any mission at any time. Since you cannot check your challenge progress in the middle of a mission, here is a complete list:

Missions

1. ​Black Ops - Complete "Black Ops" on Hardened difficulty or higher
2. New World - Complete "New World" on Hardened difficulty or higher
3. In Darkness - Complete "In Darkness" on Hardened difficulty or higher
4. Provocation - Complete "Provocation" on Hardened difficulty or higher
5. Hypocenter - Complete "Hypocenter" on Hardened difficulty or higher
6. Vengence - Complete "Vengence" on Hardened difficulty or higher
7. Rise and Fall - Complete "Rise and Fall" on Hardened difficulty or higher
8. Demon Within - Complete "Demon Within" on Hardened difficulty or higher
9. Sand Castle - Complete "Sand Castle" on Hardened difficulty or higher
10. Lotus Towers - Complete "Lotus Towers" on Hardened difficulty or higher
11. Life - Complete "Life" on Hardened difficulty or higher
12. Immortal - Complete any mission without dying on Hardened difficulty or higher.

If you follow the Roadmap, all of these will come naturally as your progress.

Tools of the Trade

1. Control Core Mastery III - Use Control CyberCore abilities against 500 enemies
2. Martial Core Mastery III - Use Martial CyberCore abilities against 500 enemies
3. Chaos Core Mastery III - Use Chaos CyberCore abilities against 500 enemies
4. Commandeered III - Kill 100 enemies using Remotely Hijacked robots.
5. Fast as Lightning III - Kill 120 enemies with a follow up Rapid Strike melee attack
6. Inferno III - Kill 100 enemies in the explosions from Immolated enemies
7. Juiced III - Debilitate 120 enemies with an electrostatic discharge
8. Shockwave III - Knock down or kill 100 enemies using Concussive Wave
9. Pulverized III - Pulverize 100 enemies using Overwhelming Force
10. 3 Laws Compliant III - Using Ravage Core, debilitate or kill 100 enemies with a volatile power core
11. Swarmed III - Kill 135 enemies while they are blinded by Fireflies
12. Demolition Expert III - Earn 150 kills with explosives

This section will take quite a bit of grinding to accomplish but as you'll be replaying missions for trophies and Accolades, you'll make progress towards most of these. The easiest way to grind this out is in Mission 7: Rise and Fall.  Your objective partly into the mission will be to plant explosive spikes into the ground. Enemies will endlessly respawn here, making this also great for grinding camos and attachments.

Career

1. Combat Distinction III - Complete all Accolades
2. Decorated III - Earn all Campaign Decorations
3. Buying Power III - Earn 80 Fabrication Kits
4. Collector III - Find all Collectables
5. Battle Hardened III - Complete all missions on Hardened difficulty
6. Seasoned Veteran - Complete all missions on Veteran difficulty
7. Unrelenting III - Complete all mission Realistic difficulty
8. Running the Gaunlet III - Earn a Tier 3 Rating in the Combat Immersion
9. Ready for Anything - Complete all waves of the Combat Immersion on Realistic

Most of these will unlock as you progress towards the  Personal Decorator trophy. The Ready for Anything challenge may take a while as beating Combat Immersion on Realistic is no easy feat. Having the Multi-Core, the ability to switch cores at will in battle, will make this easier as the most useful skills for this are Extended Camo, Firefly Swarm and Enhanced Remote Hijack. This is given to you at the max level of 20 so attempt this after you finish the Campaign.

11. Tried and True - Earn a score of 35,000 in the Training Simulator.
Refer to  For real this time for more details.

12. Full Honors - Earn all Campaign Decorations.
After earning all other decorations this will unlock directly.

Needless to say, you'll be spending a lot of time achieving all of these feats.