Okay. Telling you carpet sucks isn't being helpful. Truthful, yes. Helpful no. So I would maybe start with buying a large solid black area rug and putting it in the middle of the apartment to take away from the nastiness of the carpet. Something like this but dark to create contrast.
Then I'd remove the blinds on the window and put them in the closet for the duration of your lease. They're cheap and tacky. Then I'd paint the walls white or grey if possible. Then I'd buy a large 48" x 48" minimalist oil painting to put on that wall. Feel free to make one of your own if you're cheap and rip off Ellswroth Kelly or Franz Kline. Get a sleek frame on a thick gallery style canvas.
Then I'd look at some large scale black wooden bookshelves from some modern furniture store. Nothing too revolutionary. Just simplistic and sturdy.
Then I'd check Overstock.com and get some Le Corbusier or similar modern leather chairs for a good price. Look for a chaise lounge or loveseat too.http://www.overstock.com/Home-Garden...0/product.html
Maybe add a really high quality modern floor lamp.
Then add some spots of color or weird things to your liking for personality. Normally your taste in books for music on the shelves works to achieve this personality, but I like model ships too.
No beer signs or vintage Italian pasta posters please.