Perhaps due to her multiple career changes, it took some time for Black Widow to find her style (Avengers! They're Just Like Us!). An essential skill for a superhero spy is impersonation and Natasha has really honed her skills at that over the years. Her initial look was the fabulous but highly impractical combination of a cocktail dress and a veil. This carried over from her years as a Soviet spy to her post-defection life but didn't last long once she teamed up with Hawkeye. After all, it's hard to do high kicks in an A-line skirt. She then trialled a blue cape and mask combo, with a fishnet bodysuit underneath and (presumably dyed) black hair. Eventually she settled on the look she's best known for now- black bodysuit, lots of weapons, comfy looking boots and short red hair.