While this may be better posted in the "Show your curve tracer" thread, I figure most of those readers are well acquainted with how to use the instrument.
I have been learning about transistors recently and pulled out my Heathkit Curve tracer. I was surprised just how useful it is.
But the presentation on measurements is very clear.
The section describing measurement is attached. And for the curious, the cost difference of "real" curve tracer as opposed to a "toy" like the Thaikit is maybe $100 by the time you add in the required parts for the kits.
While discrete transistors are essentially obsolete, their study is useful if you want first principles.