Photos:
#1 unflattering building angle, looks like a Soviet style view;
#2 couch is jammed up against unit; shot only shows partial view of the room;
#3 the couches are jammed together; shot shows partial view of room; basket, green cushion and pink thing visible in right corner beside couch;
#4 too many appliances out on the counter and shot shows only partial view. This photo is exceptionally bad. You may need more than one photo of the kitchen.
#5 cardboard files/boxes lend nothing positive to the 'bedroom' image, and they suggest there is nowhere else to put them; photo is out of focus;
#6 photo out of focus; area looks windswept and lacks a human element;
#7 photo out of focus, scraggly vegetation near the fence detracts from the amenity portrayed.
You need better photos and you need more of them. Your current ones suck. Photos should be wide angle and should show as far as is humanly possible the entire room each time. If this is not possible then more than one photo of each room should be shown. You need photos that show the windows.
You need (much better) photos of all the rooms, and photos of the views from your flat. You also need to suggest where a dining table might go. If you have one in the kitchen this needs to be shown. Your kitchen seems to have a nice window area and this needs to be shown. The photo you have of the kitchen suggests there is no window and not enough room to eat there.
Staging:
You need to rearrange your living room couches. The way they are now makes the room look impossible to furnish/small. Pay attention to details like basket/green thing/pink thing appearing in photos. They suggest junk piled high out of the picture. Get rid of your visible cardboard files from the bedroom.
You need a few details such as potted plants to make the place look less antiseptic/impersonal. You can get huge plants that lend architectural interest and break up the white/beige appearance. Avoid small potted plants like geraniums. Get some rubber plants, mother in laws tongue, big frondy plants. You could also get some tall cases in different colours and put some twigs/pebbly shit in them. They are not everybody's cup of tea 
but they can draw the eye into the far corner of a room or towards a window and thus emphasise dimensions or other features.
If you are so inclined, I would paint your kitchen cabinets a solid grey, which is very of the moment. I would redo your kitchen tiling in either white subway tiles or small one inch square or small horizontal strip style tiles in some grey/light blue/silver colour scheme with maybe a pop of burgundy here and there.
Take down the pictures from the walls and put up one splotchy colourful one instead in each place where there are groups of small horizontally arranged art (living room, kitchen and the bedroom that is shown afaics). Your pictures make the flat look dated. Your new art could be posters -- maybe some political propaganda or theatre posters from obscure artsy productions in Budapest or Berlin c 1981.Look on Etsy. Or get yourself a canvas and stretch it over a large frame (three feet high at least) and produce something bright yourself with a brush and little sample pots of paint.. Figurative representation is not necessary. Just make sure you add colour and that the lines in the art as well as the art itself are vertical as opposed to horizontal, and not hung too high.
What you want to do with staging is suggest a lifestyle.
For the price you are asking, you want to suggest a chic, urban, fairly youthful but with money lifestyle here, not the lifestyle of someone who might be my age.