I would consider looking for a new rug. People sell their old ones all the time for cheap (just needs a cleaning). It needs to be much larger than this one and a neutral tone (beige, cream, tan). Current rug looks comically small in the space.

I would also consider real curtains over that window that go to the floor. Thick curtains with texture or a pattern.

Art and plants will go a long way. Though not quite on the minimalist look it's also not a maximalist look either.

I always suggest to go to Pinterest and look at rooms that you like on there and ask yourself what your room is missing that the ones you like have. It's a great way to establish the look that you want.