What’s the best way to get into Harley mechanics?

So currently I’m just a garage mechanic if even that. I have a few bikes I bought cheap that I work on and resell mainly Hondas and Harley’s. But I want to start getting into proper ground up builds and fabrication. Not just my YouTube knowledge and hoping my sketchy shit works. I’ve been told to take on apprenticeships at local shops rather than go into debt in a school. But also that I’ll get better training along with a base set of tools if I go into school. What would be best?