for a baddie aesthetic, focus on making your room more minimalist— sharp, classy and sophisticated
below is a colour palette that would work really well. try to stick to neutral tones (with the exception of dark greens, or other bold accent colours like red/purple). a white or similar colour would be really good because it's so simple to pair with
this room adds a neon pink light to accentuate. the brick wall and sofa are classier aspects, as well as the record player. it has a more mature look to it, as well as still being able to make it look like 'your own' space (the japanese sign, cherry blossom, records)
these rooms both use a mirror as their focus piece. mirrors can make a small room look bigger and are really good for taking pictures. adding the lamp and chandelier (first pic) or the couch, rug and art (second pic) further add to the aesthetic while still keeping it simple
other things to add: a vanity table to do your makeup, smaller lamps, chairs (clear plastic chairs look good especially with a small rug/fur blanket over top)