You could try out a few things that I have done to ensure natural light coming in my apartment.
Think Curtains : The first thing what I did was remove heavy and dark curtains and replace with light weight, sheer fabrics and neutral colors to let the light in. You can try roman shades and blinds too.
Swap in Glass Door : Second, I replaced my Interior doors with glass. You could do that with the front door too. If you feel privacy is an issue then, you can always go for a frosted or a tinted glass.
Mirror Mirror on the Wall : Third, came the mirror. I wanted a large mirror with a slimmer frame. This would let light in and reflect it at the same time look less chunky.
Rug in Natural light : Next, I covered my dark floor with a light coloured rug. The floor has a large surface area which can help reflect and maximize natural light.