A keyboard with symmetrically placed C and M keys is another piece of Xah Lee's sound advice: http://ergoemacs.org/emacs/emacs_pinky.html

I've been using the MicroSoft Natural Ergonomic 4000 for several years and it has improved my touch for M and C. Recently, I've been applying that on my ThinkPad [chosen because of the symmetric layout] and am removing some additional bad habits related to left-C right-C.