The Shade Tree Mechanic has gone the way of the tune-up these days, there just isn’t much use for either. Automechanics encompasses so many different disciplines you have both the use of hand and power tools you need to know about chemistry and physics and electrical theory then you need to know more than just the names of many complex systems. Figure 2 years of booklearning and practice on “cadaver” vehicles before you (not just you specificaly) are competent to diagnois the problem is the spark plugs and be able to handle any problem that comes up changing them.
This automechanics job is not as easy a many would think and many try when they have no business even trying.
Tirelessness or persistence is an excellent trait for a shadetree mechanic. If you have this, along with a cheap streak, you are on your way. I am a self-taught DIY mechanic who learned by doing every job as it arose assisted by a Haynes Manual and lately by online manuals from Alldata. I’m sure I did every job wrong at least once and still had fun and saved a lot of money. I’ve only once had to get a car towed after working on it over a span of 40 years. We’re talking Fords, too, which were high-maintenance cars at one time. Today’s vehicles require very little maintenance beyond religious oil change habits. After you do the plugs, the next job will probably be the front brake pads and maybe rotors. A piece of cake. Go for it!