This is a portrait of my wife, Aneka, that I am working on. I experimented with the ground preparation. While the last coat of gesso was still wet I broadcast into it glass microbeads, similar to the type used to make white highway lines reflective. The concept behind this was that the reflective ground would give the paint layers an added brilliance. I think it was successful.
The negative aspects of this technique are that initially the beads absorbed a lot of paint. This might be avoided by varnishing the beads layer before beginning painting. The texture of the beads was hard on my brushes and gives the finished piece a specific look, like it was painted on sand. I am not sure, yet, if that is a bad thing.