If I knew then what I know now...hmmmmmmm.
I would have not gotten married. I would have bought all the Microsoft and Apple stock I could afford and then some. I would have... Ohhhhhh...you mean motorcycles.
Actually nothing. I tried to follow everything the instructors told me and, having been a mechanic for 15 years, I know how to wrench so I don't strip screw holes. Maybe I would have bought a better helmet as my first. But when I hit the ground it did it's job and it got retired.