Get a helmet, this is a must.
Some people wear gloves, mostly to prevent callouses, or MANLY HANDS, from developing.
Some people wear shinpads, I have some (661 veggie pads) but I don't wear them too much. It reduces the sensation of shin-digs but you can still feel it.
Good, grippy shoes is often forgotten. Having some good shoes will stop your feet from coming off the pedals. I have Shimano AM40 that I wear sometimes, they turn shit pedals into ok pedals.