As a basic guideline, lights in sitting rooms, bedrooms and hallways should be hung approximately 7 feet above floor level. 

Consider that the light will look larger the lower it hangs and smaller if hung higher.

The same rules apply to hanging lights in the entrance hall or foyer, but if you have a double-height ceiling over two floors, the fixture should not hang below the second floor.

If you are hanging a light to compensate for the two-story setting, you may want to hang the light a few inches lower to ensure that it doesn't look small in your setting.