You can define your readership as “women 16 to 24. But it’s better to select your audience not by age, but by interest. Find your circle of female readers with a certain passion. For example, you can blog about jeans fashion or write about the fashion of punk rock fans – in short, specialize in a specific (and necessarily relevant!) subject.
Instead of creating another faceless blog “about beauty in general,” make a blog focused on a narrow audience. For example, a blog about “beauty for women after 40.” Let your target audience be more specific than just “all more or less fit women.” This will allow you to find the right readers (and clients), gain their trust faster, and grow successfully in that direction. Not to mention, this strategy works great for blog promotion.