Try to make sure your photo booth position is either near a window or in a really bright room, as this will help make the pictures as clear as possible. If the room is dark, you will want to get some kind of lighting.
For a lower cost, we'd suggest a ring light: it's small but will still soften the shadows on everyone's face, which is what you need it to do for flattering photos. If you want to make a bit more of an investment and have the space, then go for a soft box light. Both options are standalone lights, so once you've set them up and turned them on, you won't have to think about them again. If you have a really tight budget, the final option is to just use the inbuilt flash on whichever camera you will be using; the backdrop and room will not be bright and illuminated, but the people in the pictures will be.
