There are several options to decorate your windows. Some of them also help maintain privacy. The most common is window curtains, but there are other things you can do to make your windows more stylish.
If your window isn’t in a location that necessitates privacy, such as the kitchen, try putting some plants on the windowsill. A traditional valance performs a similar job, but you can also use painted wood or metal to achieve the same effect. For more privacy, consider frosted glass. It lets in more light without being see-through, and doesn’t need to be fiddled with. If you’re the more traditional sort, you can opt for pull-down shades, which aren’t as commonly used nowadays but do the same thing as curtains.