To unlock How Do I Look? trophy in Borderlands 2, you will need to have unlocked 10 different customisation items.
You will find customisation items by looting dead bodies and chests, completing missions, slot machines and the Item of the Day vending machines. You should easily come across 10 different customisation items as you play through the game's main story and side missions.
Once you pick a customisation item up, highlight it in your inventory and then press
to send it over to the character changing station.