The problem with any kind of measurement is that you have to know what kind of value you are expecting.
If you don't know what the signal needs to be you can't see if it's faulty.
You can know this by having theoretical and practical knowledge, or if you have a repair manual telling you how the signal is supposed to look.
My suggestion is that you find a repair shop and offer to work part time for free for a few months ( if you have time) so you can get experience.
That's how I did it, and it was worth the time
