Protective lenses if you have them. If you've got something for doing handyman-type work, those should be fine. Some sunglasses will do the job, but indoors you probably won't want those.
Also, you might want to wear a t-shirt or something else with a reasonably high neckline. Spent casings have to go somewhere, and they're hot. Different guns eject casings different ways. Until you know which one doesn't eject them straight towards your face and chest, it's worth wearing something that will keep any stray shells from going somewhere uncomfortable.