Trenchcoats and hats are great transitional wardrobe pieces.They can be easily removed or added, they add style (obvious), and when the temperature drops or rises, you can easily edit your outfit to correspond.
When I wear a trench, I tend to feel mysterious and clandestine, which I think is something everyone should experience. The hat also adds to that.
In this instance, I styled my trench rather simply, with skinny jeans, Converse, a turtleneck and a tank top over that.
I went with contrasting fabrics and prints for my tops, just to add some visual interest. Usually when I want to mix prints, I anchor it in one base color and then make sure that the rest meshes in the right way, in a sense clashing but in a totally good way.
Trench: Zara (old), similar here
Jeans: Citizens of Humanity, similar here
Shoes: Converse, similar here
Turtleneck: Zara Kids, similar here
Top: Express, similar here
Hat: Vintage, similar here
Backpack: Fjallraven, similar here