This is kinda, a no-brainer, but it still amazes me how good my home looks after we have cleared out all the clutter (right now we just move it from the living room to the office, bedrooms, or basement, but still the living room looks much better afterward).
2. Rearrange furniture
Just did this to my living room. It is more open and inviting. Don't be afraid to spend the to move the couch and TV, it could be well worth it!
I went around the house armed with touch up paint for base trim and doors. The house looks brand new. Bright white doors and trim really spruced up the place.
The windows in our 1970's home were not trimmed. So we added some molding. Cost $40 in materials and about 4 hours of our labor. Amazing, is the word that comes to mind. It looks so good, and the trim matches the door trim, so the windows look like they have always been trimmed. So smart and clean looking.
5. Hang Art
This is tricky for me, but if you have existing pictures, hang them up! I know frames can get pricey, but if you have them on hand get them out of a box or out of the basement and hang them up. Need some way to tie a bunch of frames together? Spray paint them all the same color - will look great I promise.
I know lighting can get expensive, but look for cheap lamps at garage sales and add some more light to your rooms.
Green in a room will really freshen up the space, and won't break the bank. Just one plant in the living room can make a big difference.