Buyers love to see vertical blinds on sliding patio doors. Installing these is a DIY-friendly project.
You may have a window that, for whatever reason, doesn’t need a curtain or blind. That’s fine. But, if you want to dress it up, consider a nice-looking valance.
If you have a window that looks dark, heavy or otherwise “over curtained”, strip it down.
Removing an inner curtain, for example, can dramatically lighten up the window as well as the entire room.
Replace any worn or stained curtains. There are many affordable, mid-quality curtains available that look terrific. Alternatively try sending stained curtains to the cleaners.