I agree with painting the doors. All my interior doors are a deep charcoal grey. You'd be surprised how expensive it makes them look. That aside I would start with a rug. A huge rug. Something chic with a lot of color. Then add love seats in white, colorful pillows, and chairs in fabrics that pickup the colors in your rug. No BIG furniture. Just because you have a big room doesn't mean you need to stick a brown sectional in it. A couple fancy topiary would look great under those windows. And dont forget lighting.

I personally would like to see you start your art collection. It may take a while but you will get there. And the hunt is tons of fun. Do not worry, about who made it, only that it is original or a signed numbered print of maybe 200 and that you love it. sources, etsy and Saatchiart. oodles and it changes all the time. often $100 or less. both under $60 etsy a few of the myriad ways to make your own Butterflies or some other small collectible natural or otherwise One large on subject matter, then small ones regarding that topic framed important things in your life magazines, album covers important newsprint that means something to you Bandanas, or how about the decorations off your favorite clothes before they go out. plates, or mugs, judgin by your couch, these are not it, but there are some really cool modern ones too large copies of musical scores. hope it helps

I am an amateur lover of home decorating. I too have a very awkward long narrow living room that is 350cm by 620cm. Additionally it has diagonal traffic flow from the front entry to the rest of the flat. The owners have built a cabinet at one end for the TV, etc. I think I would make a cosy seating area at one end of your long living room. Place a grey or brown sofa at one end but not against the wall. I like the idea of a narrow console table behind the sofa with a table lamp, a plant or a large statue. This brings the end wall closer in. A peachy or raspberry carpet in front of the sofa will pick up the wall colour and anchor this seating area. (grey and some browns also coordinate with raspberry/peach). A couple of raspberry sofa cushions can help include the wall colour into your overall scheme. Single chairs opposite the sofa allows visual and actual flow down the narrow room and completes this seating area. At the other end of the long narrow living room I would place a reading chair, a floor lamp and a small round coffee table. If there is room you could have a tall bookshelf with you favourite books. What do you have on the long side walls? I have windows and doorways on both long sides. I decided to use pull up shades on the windows instead of curtains which I thought would make my narrow living room look more narrow. The wall colour is white but I think I will tone it down to a soft grey. I plan to paint the end walls a darker grey.

The balcony is nice. I once made all windows in an apartment a standing balcony. I placed artificial turf and some climbers in hanging pots from the ceiling with small lamps. For more dramatic look cover the ceiling with wooden panels (water proof).