Complete the task or action and then you will unlock the reward shown.

Avenger jacket - "3 Gold Star" rank in Gang Kills.
Bodyguards gang style - Progress through the game.
Brotherhood personality - Brotherhood mission 11.
Chop shop - One Chop Shop list.
Fireman outfit - Complete the Firefighter missions.
Free Music track - 10 CDs.
Free Music track - 20 CDs.
Free Music track - 30 CDs.
Free Music track - 40 CDs.
Free Music track - 50 CDs.
Ninjas gang style - Progress through the game.
Paintball mask - Complete 25 muggings.
Pimp suit - Complete of Ho-ing Diversion in Red Light District.
Red Light apartment crib - Prologue mission 2.
Ronin personality - Ronin mission 11.
Saints hideout - Prologue mission 3.
Samedi personality - Sons Of Samedi mission 11.
Traffic cone hat - "3 Gold Star" rank in Vehicle Surfing.
Zombie mask - Complete Zombie Uprising.