I started out as a sheet metal mechanic 1987 and progressed up to CNC machines, writing and programming code. At that time I started intergrating my cad skills along side this. I have been using various types of CAD software for the past 17 years. Mostly AutoCAD, but since 2010 been using Solidworks. I have gone through some of the Solidworks certification classes, such as solidworks essentials, sheet metal, weldments, drawings.
Grad school and some college. But I think experience speaks more than any book could have taught me.