Well, the sofa is great! And the bookcase is… very middle American. Right now, you have a focal point that doesn’t actually exist, and that appears to have been built to house a collection of books you don’t have. It simply doesn’t work, and is unattractive to boot — but you’ve invested in an immovable object, and with a little rethinking, it should work.
Start with the books — don’t respect the horizontal visual of the sets; that sort of display is very out of date. Stack them horizontally, mix them up, make sure that you have a good book/object-to-shelf space visual for each vignette. Bring in *more* books! There should not be a lot of air over books you set up on a shelf — usually, you don’t want more than an inch or two from the book to the shelf top. This isn’t true when you group small books with a larger object such as a vase, of course. Think of it as a process of layering — you don’t want a vase, you want a brightly-painted wooden jointed snake sprawled over a coral knob on top of Grandmother’s orange mitten in front of a vase on top of a couple of books in front of an set of instagrams.
You will need to do some research, which this site is excellent for, and figure out what you have to use as display materials. I think that those little colored objects, which stand out so nicely, prove that color might be your friend in this — if you can mix unifying doses of grey, to echo the couch, along with big pops of bright colors to lift the mood of the room, that would be a good idea. The table and chairs prove that you aren’t afraid of color.
Gather up small paintings, pictures, mementos, collectables — I don’t think you’re going to be able to go with ‘less is more’ in this situation. Go with ‘more is more’. Once you have about twice as much as you think you need, invite a friend with decorating taste you admire over, and ask for help in just FILLING the shelves attractively. Think ‘vignettes’. Then, over the next week, tweak the display until you’re happy with it.
I recommend offsetting the TV, perhaps to the upper right, and vignetting that as well, with a primary piece of art and a large piece of statuary or pottery. Deal with the cord issue! The speakers need to be housed on the shelves, discreetly incorporated into the display, and if the white objects are gaming systems, find some way to consolidate them and put them behind a sliding panel. If this is simply where all the electronics in the house have migrated to be stored — this is NOT the place for mundane tasks.
Consider painting the walls a complimentary light grey, and then bring in bold, primary-colored rugs, cushions and art. Mix a few patterns!
Did I mention how much I like your tablecloth? That is the commotion of color you need to take across the entire room. The black-framed pictures are great, but obviously need to be rehung — again, this is a matter of research. There are many pictures on this site and on others that show how to achieve a modern layout of art; you just have to put in the time.
Replace the small storage unit in the dining room with something impressive — if you can’t match the dining set, go for a colorful mexican-style buffet.