Edit: the duality between "lol get curtains" and helpful things is great. But! I can't put up curtains on the windows the light floods in - it's the front door and the sort of side window beside the front door.

I also didn't want to put holes in the wall, so I got command strips (those little stick-on / pull-off hooks) and used them to hang my curtains. If the way it looks bothers you, you could hang a piece of decorative cloth in front or back of the curtain.