When water flows into smaller pockets of a stream, what tends to happen? You'll probably observe a pool of water swirl in a spiral, staying in one area. Or it could become stagnant, resulting in no movement at all. 

This would be the feng shui metaphor within your home when corners go unaddressed. 

Each persons situation will be different with how to address their room's corners. Simply put, know the function of your room, it's needs, sided with your intentions of attraction using the Ba-gua map. That will indicate what could be placed within the corners. 

Quick General Ideas To Help Address Your Corners

• Artwork along the walls near the corner
• Plant stand or vase with plant or hanging plant
• Corner shelving
• Reading chair, corner desk, bed, table or other pieces of furniture 
• Standing lamp or hanging lamp
• Painted color on the wall itself

It's best to work with a feng shui expert one-to-one as to provide customized recommendations. For now, these general ideas offer a great starting point.