when advertising anything, weather it be a service or product you must be careful about the way it may be perceived by others . A simple pose or piece of text could come across offensively or like a generalisation.
Image from Wix.com
For example the Maasai Tribe believed they are being invaded by photographers and weren't respected by them. often images were sold without their consent.
if a model features in any form of photographic work they must sign a model release form like the one below, these can be found on The Association Of Photographers website.