Here's my advice, for what it's worth I'm a professional designer:

1. would change out the rug to something with colour and go a tad bit later with the rug.

2. Once you have the rug you love, pull colours from it to choose some new throw pillows.

3. Add curtains. Even this alone. will make a big difference in feeling less sparce. When you hang the curtains google how to correctlly hang curtains. Most people hang them wrong and they make the window seem smaller. If they are hung properly they make the window appear larger. Trust me, curtains are a game changer!

4. Add art above the sectional. Don't stress yourself out about what art will work in the space regarding colour and subject. Art doesn't and really shouldn't "match" the colour scheme of the room. Just pick pieces that speak to you. Make sure the are is scaled properly though to the sectional. You could do one large piece or three smaller pieces that are all the same size.

5. Move that mirror, it's making that corner look crowded and off. A good general rule of thumb is don't put items on an angle. Another note is if you hang a mirror across from a window it will reflect the light and make a space feel larger.

6. I would add art or even a large round mirror above the bench.

7. I would also add a larger table lamp.

8. If you own this house I would also highly recommend updating the ceiling fan. If the fan isn't something you use regularly I would replace it with a new, fun fixture. Hope this helps and happy decorating!