Posting with permission from and credit to MSFT Marine from X360a
Head -> Body Art -> Day of the Dead (Las Catrinas)
Tops -> Gloves -> Bucky Gloves (Bucky)
Bottoms -> Bottoms -> Fargarthian Armored Pants (Fargarthian)
Tops -> Outerwear -> Troop Member Vest (Troop Bushido)
Tops -> Tops -> Polo Shirt (Oxfords)
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You get faction-specific clothes from doing side missions given from the factions. The example he gave is just one of the possible combinations.