Hi there! Decorating in a rental is always a challenge, and a basement suite is even worse with low light levels, poor planning when developing the space, etc.

I think you could make this space cute, though, by creating a color scheme that you stick to, so you can create a cohesive look. Using your dark green sofa as a starting point, maybe use different shades of green, along with some yellow (because of the wall color), for a light spring or summer look that will brighten your subterranean space.

Showing below some pillows, curtains and an armchair from Pier One that you could purchase as your budget allows. The first pair of curtains is the Pier One pair (called Green Ripple), and they are on clearance. The second pair is called Mariam, from IKEA, and are super cheap.

Furniture arrangement: the sofa should go on the same wall as the red checked one in the pic, but centre it under that window. When you can afford an armchair, place it at a right angle on the side of the sofa that is closest to that hall doorway. If some of your IKEA bookshelves will fit along that wall, you could place them there, behind the chair.

The wall that the entry door is on could hold the electric piano, centred under the window. And, the small niche where the last tenants had their TV could hold the canvas screen you are planning to make, with your wicker bench in front.

The idea of the curtain panels is to dress up the windows, as well as add a splash of color to your room. Don't worry about trying to disguise the fact that they are basement windows. Just mount the curtain rods wide enough so that the curtains, when fully open, aren't blocking the windows at all.

And, the pillows for the sofa are not only going to make your room look cozy and inviting, they will add some pattern that will otherwise be difficult to get, since it doesn't look like you have room for wall art.

As you can afford it, end tables, a proper coffee table, and lamps will add to the warmth of this room. Tip: don't buy all your coffee/end tables as a matched set. But, we will worry about that when you get to it!

Thank you! I never would have thought to put the wicker bench under the screen in the nook, but that could totally work. Also, I love the idea of incorporating some of that lighter green. I had been worrying about blending dark green and the much lighter yellow, so they go together. I think pillows like those would totally help make the transition. All your other suggestions seem like they would fit the space as well. Plus, I always wanted a good reason to save up for a cute arm-chair.

One question, would I hang the curtains right near the ceiling and have them hang nearly to the floor, or is there some better proportion for these little windows?

I would go as close to the ceiling as you can get. It will make your room appear taller. And, yes, just about touching the floor is perfect for length.

Perfect. I move in May and am thrilled to have a place to start instead of slight panic!

All the best to you, and have fun making this little suite your own!