I also liked "muscle confusion". That always worked well for me.
   My first learning was weird though: I was about 12 yrs old and a
   Boy Scout. In the back of a Boys' Life magazine (the magazine
   for Boy Scouting) was an ad for "Charles Atlas". I scraped up my
   change, got a small job after school. Once a month I got a 12
   page photocopy full of exercises, "you can do it advice" about
   something he called "vim and vigor" dated from back in the
   1930s, showing a old-school strong guy in his underpants (if I
   was lucky) doing these exercises where you pitted your muscles
   against each other. No weights, maybe use a chair.

   Anyway, the stuff worked*smile emoticon*By the time I was
   allowed to lift weights in school, I was already ahead of the
   others*smile emoticon