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 low 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.