You might start by replacing the brown armchair with something that is a bit more fun, and then spin your ideas off that. To me the chair below suggests black and white throw pillows on the couch, with the addition of a good, sharp accent colour, too. Then I might take the accent colour and use it to paint the backs of the shelving.

Accent Chair, Black and White Bird Pattern · More Info

I'm also thinking a few big, striking items would bring oomph to the shelving (think white or strong colour and strong shapes), and that perhaps the wall disappearing to the left might be a good place for a piece of art that lifts the mood.

Yes, I think one chair is enough.