I've painted lots of people with glasses. I found it easiest to paint the faces WITHOUT glasses first, then add them on a new layer. Same with lenses.

Another method for creating a "painted" surface (different from my Andy Warhol post). In this instance, I wanted to have the scene look like a painted canvas in a style similar to Frida Kahlo's paintings.

"Shiny stuff" appears in all sorts of places. Learning how it reacts with light and surfaces makes it fast & easy to paint these details convincingly.