I don't know wath you wanna do but i can give you advise to make it cozier. Try a light wooden floor and white or earth color walls. Get some grey thick curtains that will match the rest of the room. And other light bolds some warm color instead of white. I hope this helped you :)

I think I would address the ceiling first. Tenting it with and inexpenive fabric such as muslin or monks fabric will disguise what is above the beams.

What is that large brown piece of furniture dividing the room - an entertainment center? And what functions do you want you living room to serve - entertaining, conversation, games, TV, study or something else? Your answers will help guide us with our suggestions.

THANKS, MANON FOR YOUR KIND SUGGESTIONS! IT GIVES ME NOW AN IDEA!

You are most welcome! I'm glad I could help.