There are so many blogs out there fashion wise of course. Your thinking of starting a blog as your business not just for fun. You need to set this up as a business with a business plan.You need to figure out what in the fashion industry you would like to blog about. Example DIY fashion , star fashion, how to outfits. Those are just a few examples. You will choose the main topic and start writing a few post. See which ones you think would make great blog post and get started.
Ads- You would need to make money from this blog due to this being a business not just for fun. You can sell ad space for $30- $300 per ad space depending how good your blog is doing. Such as followers and daily page views. If you get thousands of page views per day you can get money for ad space. With this alone you can make 3,000-10,000 per month.
Affiliate- you can make extra money by promoting products with clickbank , amazon, adsense and more companies. When your readers click on items you can make money. When they buy items from amazon that is promoted by your blog you can make money from each purchase.
E-books- add some creative e-books to your blog. Diy fashion and much more. Also connect it to amazon which you can sell your e-book and make more of a profit.
Keywords- make sure your post has rich keywords, this way google will pick up your site and pull it to the front.