It looks cozy and clean as it is, so you're off to a great start. You might want to get a small piece of furniture with drawers, if you'll ever have longer term guests (more than overnight). It's nice to be able to unpack a few things, esp since it looks like there isn't a place to keep luggage handy. You could put the chest or bureau in the closet to save space...or see if one could double as the 2nd night stand (looks as if it might be too cramped, but maybe?). A chair is always nice or maybe a small bench instead of a chair at the foot of the bed. If you got one with storage, you could keep extra blankets and linens in it. A folding luggage rack kept in the bottom of the closet might be welcomed by your guests.
Of course, art will add a lot. I'd probably lower that one piece we can see already on the wall.
Since space is at a premium, maybe think about a faux headboard to add color to your room. There are a gazillion ideas on pinterest:
Painted on:
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Old look
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