This is a topic near to my heart. Before I started developing, I was a system admin who dreamed of coding. In my spare time I started to write Autocad scripts in C# for the Engineers in my back office.
I read this blog (among others) to get me started.
I would start with what you know, which is probably includes ADO and build some functionality into what you are working on currently in the CAD world. Again, for myself, we had an IBM mainframe with customer data and Engineers handwriting worksheets designed in CAD. I took the two and married them into a pretty successful utility application that ran right inside of the engineer's copy of AutoCAD. Now they just selected a customer they were doing work for and it populated the text fields inside of the worksheet, and there was much rejoicing yay.
At any rate, enjoy the experience.