Paint and decorate in light colors. Dark colors absorb light. Light colors reflect light. The lighter the colors you use, the less artificial lighting is required to illuminate the area. Check your lamp shades.
Many shades are decorative but absorb light or reflect it in the wrong direction.
Without us attempting to be your interior decorator, you may consider switching to a more efficient shade in a lighter color. Install separate switches for smaller areas. Often in large buildings, dozens of lights are controlled by a single switch, and not all of them need to be on. These lights can be rewired into smaller groups of lights on independent switches. This way only those that are needed can be turned on.