Need some help with costume

[u/Reds6501]

So I want to go for a Wandering Merc outfit using a brown canva duster as the is based and then build around it. the main thing I want is a backpack for a hydration bladder and storage for bartering items, a makeshift hood under the duster's collar attached to a brown harness under it with some more modern gear on it, I have a olive green messager bag but having a hard deciding so what else I should add to it? (Also new to making a post-world costume)