Get furnitures you really like! It sounds like the floor and walls are pretty dark. I would go with very light colors. Like a white couch. To add some color accents you can pick a red which goes together with the green floor. And to brighten up the floor you could think about a rug.

whoever floral couch must have come here in a time machine from 1985

I'd pick furniture that could work in other spaces too, go nuetral-black, dark brown, tan, gray things that work with most color schemes and that you'd bring to the next place

Bright floral couch set would make a nice statement. Honey oak and even birch will also go good with your Pandorian colors.

There is no hope and you would be dumb to buy furniture to match such decor.

I moved into this rental and I have to go purchase furniture soon.

The issue I have is I have no idea what goes with the ugly forest green carpet and wood panel walls. It's looks like an upside down tree. Ripping up the carpet or changing this is out of the question.

So what colors am I going to be working with? Is there anything that will go with this without looking so dull and old?