If I was trying to sell I'd get rid of the wall paper. Even if you find a buyer who likes tiny floral patterns (and in most cases you need an entire family who agrees they like the pattern

) it's dark, busy and makes the space look smaller.
Speaking of paint: light colors "bounce light" and make spaces look bigger. The door at the bottom left, paint that too.
The swatch of dark vertical paneling in the bottom left photo? Gotta go. All these lines, like the bottom left room is fairly neutral but has the trim that's a different color? Gotta go.
So pick
one nice, neutral, bright white or off white and paint paint paint paint.
Window treatments: Those dark curtains have got to go. The ones on the bottom left side which appear to be hung off a rack style of thingybopper. You see how the edges of the structure touch the walls? It just emphasises the small space. If only in that room you've got to find a different way to hang curtains or it's curtains for your sale
Hint: shiny things bounce light and make rooms seem bigger. I'd look for new curtain rods like brushed chrome. Makes buyers say "ooooh, shiny shiny."
Look for window treatments that are light, bright, simple, clean lines. Consider replacing the lace ones too.
To paint you're going to need to clear the space. I'd declutter ruthlessly. If you don't actually touch it every single day, gotta go.
Imagine the space spare, bare, practically Spartan, with clean lines, lots of light and light colors it will
look much bigger. Often that's all it takes to make buyers say "yes".
So my plan would be to de'clutter, clean and prep and paint (Hold off on the carpet decision till that's done. At minimum it's a tarp

), then accessorize with spare, simple lines.
Trek ~ CCA class of '83 ~ 420