There are many types of under-painting. I have a demo on my site from a workshop in Atlanta last year at
http://www.fineartportrait.com/workshop_demo.html Maybe this will strike a chord?
I assume you went to school for a number of years to become an engineer. Is art any less legitimate than engineering? I would suggest you consider taking a workshop that would clarify a sound working procedure. I could probably recommend someone if you're interested ;-)