Often in Interior Design, beginning a new project can be difficult. If you are starting over or you have a very neutral palette to work with, a good place to begin is with the windows. Though, some do not care for drapery panels or valances, they can add a major "wow" factor to any space.
I like to first determine what type of window covering is needed or desired. For instance, if you have a room with shorter ceiling heights, but you would like to give the illusion of a higher ceiling, you can hang panels on either side of the window, from the ceiling to the floor. This gives your room the illusion of being taller while also adding a dramatic focal point. Another example is if you have a window that you do not wish to cover (because of the light it lets in or the nice view) you can create a valance to place above the window to add a little bit of interest.
Fabric &/or trim for a window are a major factor. The decision on what fabric &/or trim to use is based on the room & overall feel of the space. Some like a more dramatic drapery, while leaving other pieces in the space neutral. While others prefer a completely clean & neutral palette all around.
You can use trim (also called fringe) on a window covering or panel to accent or to create a more formal feel. The types of trim that are commonly used on windows consist of tassel trim & tape/banding trim. While tassel trims are considered more traditional they add an air of elegance to a formal space. Tape trims are more popular right now in interior design because they are more casual & create cleaner lines while developing a finished edge on a panel or valance.