Was messing around with the wardrobe for my new thief (pistol deadeye - pew pew pew!) and came up with this look I'm really happy with, which I call the Wyld Wanderer. The backpack is the basic one from engineers, but really finishes off the lone explorer look.
I see the character as being a sylvari who felt their wyld hunt called them out to simply travel, explore and help out on a small scale where possible (rather than being some great dragon slaying hero), and carries her whole life in her rucksack. If that help also involves going pew pew pew with her pistols, then that's a bonus.
Chestpiece is from the ascended armour. Other ones that help fit this look include -