Download Lightroom presets and LUTs, absolutely free. Use the presets to add creativity and style to your photos.
Now change the foreground color to black or just hit D then select the background layer and hit Alt+Backspace to fill it black. You'll notice that there will be some thin white bits around the model. So select the layer with the girl on it then click the layer mask button at the bottom of the layers panel. Now select the brush tool and choose a soft round brush about 50px diameter and 50% opacity and make sure the foreground color is still black. Now just draw over the white patches just to blend the black of her clothes into the background. After you've done this do the hair but change the brush opacity to 100% then just roughly blend the hair into the background. After fiddling with it for a while you should have a result like below.