I think a few elements are essential for a cozy space.
Softness - pillows, rugs, drapes. A bed you can fall into.
Lighting - multiple types and layers of light, task, overhead, ambiant.
Color - I love a white room and they can definitely be cozy, but they need the other two elements to be so.
I personally think living plants add a lot to a space as well. Mine are currently small, still searching for the perfect plants for the light conditions in the room. But the bathroom has plants too.
In my space, I've incorporated all of the above, and the cherry on top, is a rocking chair in front of the fireplace, with a hand knit blanket, made by me. A hot beverage, a book (variety provided in room) or a movie on the TV, and it doesn't get much cozier than that. Maybe a cat in the lap, but I'm currently blissfully pet free.
Any tips on turning an image?