I wear a helmet. I very likely will regret not wearing gloves the first time I go over the handlebars with my hands outstretched and my palms loose most of their skin to the pavement. Other than that, I don't know what else I might wear to protect me on a paved trail or road.

Oh yeah, glasses. Never ride without them. I had a dragon fly hit me square between the eyes. It hurt, even with the safety glasses that I wear.