Find an inspiration piece....like a piece of clothing, artwork, or a pillow to get your inspiration colors for the room. Then build on those colors. Bring in smaller furniture that fits the room well. You can always Re-do the old furniture with paint to match the new decor. Bring in Accent pieces that are practical for a small room.
My daughter has a room the size of a closet. We bought her a new captains bed where the dressers are built-in underneath and at the end of the bed there are bookshelves. This helped design her space in such a small bedroom. This way she doesn't need a lot of furniture in the room. She has shelves on the wall to store all her knickknacks like kids do accumulate. I found the same bed for you if it might help with a small bedroom. It is extremely compact for a small space. We bought the Lulu loft bed by Ashley just in case you are interested.....
I hope this all helps you! A small bedroom is always difficult!
This may give you a few ideas: https://thehoneycombhome.com/dorm-room-day-kover/