According to Philip Kotler, father of marketing, a niche is –
‘A portion of the market in which individuals possess homogeneous needs and characteristics and the latter are not covered by the general offer to the market’
Well, fashion itself is a broad term. It encompasses a wide range of clothing, accessories, make up etc from various genre, style and brands. It varies from season to season, by region and personality. Before you go on writing about fashion, know whom you’re writing it for and what they like or want.
You can not please everyone all the time, so it’s wise to choose a niche and try to create a loyal follower base. This allows you to focus all your efforts on making amazing content, meeting your audience expectation, and maybe slightly less competition. Most importantly, this allows you to stay true to yourself.