Hi Jacob—
Great questions for sure!!! I don’t think that there is a standard approach to a Trompe L’oeil work any more than there would be with Figure or Still Life. My earlier works indeed started with a more general “lay-in” (as many employ today) but I quickly began to question why I couldn’t do more in these early layers. I do understand that there could be some broad contextual issues that arise from working this way—but experience has allowed me to contend with them (hopefully) successfully.
As to sketches/cartoons—again, mine are fairly simple (and seem to grow a little simpler each year). So much so that I think some might even go so far as to describe some areas as a visual survey as opposed to a developed cartoon. Lol! As I have mentioned before, I truly enjoy doing most of my drawing with the paint and I believe that this is evident in my start. However, you can see me using a slightly more developed cartoon work from my piece “Discovery” found in the WIP section here:
http://www.smartermarx.com/t/painting-photos-video-small-shadow-box-still-life/82
This piece (Discovery 7x5", Oil on panel) was used for the Language of Painting DVD series.