What exactly do you want to do with AutoCAD ? Infrastructure ? Electronics ? Rolling Stock ? Because each area and others have various tools, stuff like Rolling Stock is much more advanced involving materials, structural, 3D environment, virtual analysis etc... AutoCAD is just a tool of the trade, I keep telling my brother in law this, as he wants to grow his income but is focused on CAD rather than what he does with CAD
I've used CAD systems since the 80's, started using AutoCAD in 1990 on Solaris Workstations which was ace, moved backwards onto MSDOS then Windows versions - I still use AutoCAD occasionally, but my career is more focused on report writing, audits, supervision, checking, specification, costing...
The key thing is AutoCAD skills are as important as having Word/Excel skills, but unless you are a trainer in them, they are not the job