Elaborate backstories are well and good, but one of the best and most evocative pieces of character-driven roleplaying I ever saw was a dragonborn fighter who’d make a point of hitting up the local moneychanger every time the party visited a town to swap one gold piece for a hundred coppers, which she’d keep in a pouch on her belt, and for the whole rest of the session she’d randomly describe herself snacking on those coppers like potato chips.