^This. I just started out last year and watched a lot of different vids to get ideas of what processes to use. I'm not sure about the online classes, but a "hands on" class would be the best way to learn. You'll find what works best for you and your situation through trial and error with hands on practice.
What kind of work are you looking to do?
Of course we all want to do high end details, but it takes time to build a customer base, and most common people just want "clean and shiny". Start off with the basics and build from there.
A very small percentage of my jobs are paint corrections. Most are just heavily used dailly drivers, family sedans, SUVs, and minivans, where the main focus is the interior. All you really HAVE to have for them is a good vacuum, some brushes, and the proper cleaners. Extractors, an air compresser, and steamers may help speed up the process, but you can get great result without them for now.
I you have the cash to pick up a DA polisher and pads(lots of pads), you can start by practicing on family and friends cars.