Hello Mike and welcome aboard. I can totally relate to
The problem (as mentioned by others) will be finding enough time to practice and build up experience.
Often when using a scope for the first time it raises more questions than answers as you can now reveal so much more. This therefore means you have to develop a deeper understanding of the circuit under test so giving you the ability to analyse what is and what isn't valid detail within your waveform.
I would always recommend you scope as many good vehicles as possible (no faults evident) as this will enable you to build your own library. You can then introduce faults into vehicles and look at the effects upon your waveforms before and after.
Remember you can use the software from home, downloaded onto your PC-Laptop, where you can run in demo mode for practice or open saved waveforms from vehicles measured during the day. This gives you quality analysis time as you are removed form the hustle and bustle of the workshop
Any concerns you have Mike, share them here, there are no stupid questions. Enjoy and take care.......Steve