If your bathroom has a window, regardless of size, by using a rollup shade and valance, you can make the window appear larger. When curtains are hanging down, they often close off space. Having the shade pulled up and just a soft colored valance, you will be amazed at the difference. The calmer colors such as off whites, neutral colors, and pastels can make the room seem larger. Stay away from bright colors and bold patterns on the windows, shower curtain, or walls.
Another trick is to paint the woodwork around the window and doorway, cabinets, and door the same color as the wall. Rather than having several visual stopping points, you will have a smooth, even flow.