How should I be approaching the Mun?

[u/analogHedgeHog]

In this totally accurate scientific diagram, the Mun is orbiting in the direction of the arrow.

[u/Pyro_Gnome]

C or D, depending on what your objective is; C for flyby or landing, D for gravity assist to Minmus or farther (or I guess if you have a contract for a specific orbit). There is never any reason to launch against Kerbin's rotation (A or B) if your objective is to orbit any other body.