Bonus Headgear items: 

ICS-PL Helmet:
Have a saved game file from Rainbow Six Vegas saved game file.

J-E FO Helmet:
Have a saved game file from Splinter Cell Double Agent saved game file .

PAS GT Helmet:
Have a saved game file from Rainbow Six Vegas saved game file.

Tactical Shemagh:
Have a saved game file from Splinter Cell Double Agent saved game file. 

Decorations:
Accomplish the indicated task to unlock the indicated decoration.

Master Tutorial Challenge 1:
Destroy all of the enemies without taking any hit.

Master Tutorial Challenge 2:
Execute all the enemies with one headshot per enemy. 

Master Tutorial Challenge 3:
Blow up the tank using only one satchel charge. 

Master Tutorial Challenge 4:
Have your team kill all 5 enemies. 

Mission Accomplished Decoration:
Accomplish all secondary objectives. 

Single Player Master Decoration:
Unlock all other single player decorations. 

Tutorial Walkthrough Decoration:
Finish the tutorial. 

Act 1 decoration (elevated risk):
Finish act 1 under elevated risk. 

Act 1 decoration (low risk):
Finish act 1 under low risk, normal risk, or elevated risk. 

Act 1 decoration (normal risk):
Finish act 1 under normal risk or elevated risk. 

Act 2 decoration (elevated risk):
Finish act 2 under elevated risk. 

Act 2 decoration (low risk):
Finish act 2 under low risk, normal risk, or elevated risk. 

Act 2 decoration (normal risk):
Finish act 2 under normal risk or elevated risk. 

Act 3 decoration (elevated risk):
Finish act 3 under elevated risk. 

Act 3 decoration (low risk):
Finish act 3 under low risk, normal risk, or elevated risk. 

Act 3 decoration (normal risk):
Finish act 3 under normal risk or elevated risk. 

Quick Mission Decorations:
Accomplish the following task to unlock the indicated decoration.

Bullz Eye: Have 100% accuracy. 

Predator: Have all fights engaged by you. 

Iron Man: Do not take any hit during the mission. 

Hawks Eye: Obtain all intels out of combat. 

Team ELITE decoration: Do not take any hit your teammates and have 
50% of the enemies dead by your team. 

Quick Mission: 

All weapons: Finish the entire game.

Theatre options: Finish a level to unlock its theatre options.

Character info: Unlock 5 decorations.

Weapons info: Unlock 10 decorations.

Music videos:

Gimme Danger music video: Accomplish Mission 1

Battle Axe music video: Accomplish Mission 3

Hero music video: Accomplish Mission 7