Even mannequins have a skin-tone! Pick the right clothes to go on the right model to enhance the clothing because it is enhancing the visual image you are portraying.
Your staff are your best promoters, although customer service has pretty much been ignored in training these days, they could be wearing the garments of yours that are at least making them look as if they are professional and approachable.
Advertising banners, posters, print and media. Please put the models in the right colours, sometimes they look positively sick!