Clean up the glasses, sounds too simple, but it really works. After days of dust and days of rain, you may still look out, but it is blurred, and the sun is not completely shining in, how is it possible to be bright?
Try to use a light color to paint your window frame, even if you don’t want to enlarge the size of the window. The light color can visually give you the feeling that it is bright, and light after travels through glass can bounce on the frame and wall, which will also bounce more actively than a dim color frame.
Try not to place the colorful glass with, if you insist to reduce the sunshine, place light color rather than which can not let light pass completely, or the window is big for that.
Try to hang sheers to cover the sun in the daytime rather than deep color glass or heavy curtain. Sheers are light and allow light to pass even if it covers, and it is a good option to be decor.
Try to use a light color curtain, unless the color of the room is very light. It is a good option to place linen curtain to cover completely when you need to sleep, and the material is very healthy and skin friendly to any ages. But if the wall and most of the furniture are light color already, it is not bad to place dark color curtain, to look contrast.
Remove any subject which causes cover up the window like decoration. If you really like them, try not to cover the whole window.
Don’t cover the window with high furniture, rearrange, please. After you place the furniture where you may look the furniture is brighter, but the room will not.