I'm late to the game... Trial and error, along with being brave enough to realize the bike "may" not run as it did before jacking around with it, "possible" broken parts, a "necessity" to buy new tools (yay!), and being the friend your buddies ask for help when they want to do something.
Doing something on BB first, then being able to help a buddy with the same thing has been invaluable. Takes less time too! All but one buddy had their clutch and brake fluid changed, coolant and motor oil changed, and miscellaneous items done. Something that should take 2 hours usually takes me twice as long, because I usually need something from the apartment (wrenching in a parking garage sucks), a new tool, parts...
I work in the juvenile justice system and youth always ask me on Monday's/Tuesday's why my hands look dirty. I sometimes say, "Do you see any pictures of a wife and kids in this office? Nope, just motorcycles. Guess where my hands became dirty."
Question: Does anyone owning a Busa ever "finish" tinkering? I never remember doing all the additions and modding to my GSXR 600, SV650, or Interceptor VF700F. I loved that darn SV to death and put a big chunk of cheese into full fairings, a sargent seat, and exhaust (before being abruptly stolen 3 days after installing the seat and exhaust). Am I digging myself into madness always having a "project" for BB?