Easy New Art. Speaking of artwork, sometimes you can get the best results by making your own. Of course, making extensive artwork is time consuming and possibly a challenge if you aren't an artist! There are a few good extremely easy art projects that can add a new feature to your room with very little cost and work.
This project, for instance, is one anyone can do: take scraps of wallpaper that complement your room, frame them, and hang them for something that looks professional but takes no time at all to make.
Fresh Plants. The instinct is to grab flowers and fill vases—and that's a great way to decorate! But you can also use green arrangements or just new green houseplants. Not only can you keep them around for longer, they also freshen the air. If you're not too sure about adding plants to your house, do some research to find some good, low-maintenance choices.
Use Sheers. While you don't want to use sheer curtains on windows that face directly East or West (they'll see direct sunlight and can make the house both brighter and hotter), sheer curtains on less-intensely lit windows can provide a soft natural glow to your house that is a proven mood booster.