Here's what $50 bucks and 15 minutes can do to a room. I have a huge space if you think about it: 10ft ceilings, an open floor plan, and plenty of light thanks to gigantic sliders that span the width of my studio. Still, light is an issue, especially at night. Here's what I did with five, $5 full length mirrors from Target.
First, affix 6 3M Command Velcro strips (1 package per mirror= $5 per @ $25 total)
Lay out, measure, level, and affix to wall. Total time: 15 mins.