What size is that bed? IMO you need a queen for guest room and we need a to scale floor plan with all measurements marked .Also window and doorway placemnet

Looks to be a small room. I'd consider putting at least a full sized bed (preferably a queen) in front of the window and let the window serve as the headboard. Install blackout blinds and remove the curtains completely. I'd find a chair that is appropriatly sized for the corner where the bed is now. Any chance you can replace the closet doors with something nicer? What is the space above the closet? Perhaps you can use it as a bookcase? Have fun.

what are you using it for? guests? office? kids?

paint, new blinds (if doing curtains, they've got to kiss the floor. no high-water drapes) , new light (or fan) art, shelving.