Guitar Nerds Anonymous

If you are recording, get 2 small diapragm condensor mics, one close, one further away. blend as necessary.

If you need to use that guitar and a mic in a live situation, use a shure sm57 approx 8 inches from the soundhole,

lol, everyone's a sound engineer.
There are many situations where your advice will work, but more where it won't. This all depends on the room, the guitar and the player's style. That's without even going into the type of music and (if any) number of other instruments on stage.