I have done diy servicing from my first car - a 1929 Riley Nine.
Modern cars are easy: just buy a decent code reader, and a proper set of manuals.. and look after the electronics..Learn simple electronics and get a decent digital multimeter.
Apply logic and ensure you buy no car designed by the French..:-)
If you buy a laptop diagnostics system, and know what you are doing , you will be better than 90% of all garages...