Your choice of wall art
This is arguably the most telling part of your room, since you are given a blank wall upon which to express yourself as you please. And you should use that space! No décor at all is serial-killer creepy, and/or the sign of a really boring human.
Posters procured from a sale at your college bookstore are all no-nos: the cliché beach scene, the Napoleon Dynamite movie poster, the two lipstick lesbians kissing in embrace. This tells her nothing about you or your interests, other than you’re too indolent to shop for real wall art. Photos of your high school basketball team mean you’re still basking in your glory days from more than a decade ago. Was that your life's peak?
A flag of the country you studied abroad in is great convo fodder if she also studied in Barcelona. But your parents probably paid for that semester of clubbing-and-sometimes-class, so if you still dub it "the best time of your life," she may wonder why you haven’t traveled further than that damn beer fridge since. Race medals and numbers say you’re a dedicated individual; but if you're rising at 7am for a training run, she's staying in bed.