With curtains, because they are so large, it can usually be a good idea to pick a neutral color so that the curtains recede into the background effectively. Especially if your room is busier or more colorful, selecting a white or cream color can help make the room feel less heavy.
However, on the other hand, if your room is mostly minimalistic and in lighter colors, selecting a curtain or drape in a bright jewel tone can create a dramatic focal point in your room. Consider a bright green or royal blue for a gorgeous statement piece.
Patterns can spice up your interior too. If there are no patterns currently in your decor, you can go with a bolder design to draw attention to your beautifully decorated window. If you already have patterns in your room, for example, a geometric or damask pattern on your cushions, try choosing something that will match the current style for a cohesive look.