The way you pick up a guitar and hold it naturally is the way you need to learn. For me, that's left handed. It makes buying and borrowing instruments very difficult, but then nobody ever borrows (and possibly trashes) mine!

When I was first learning, I played both ways round - my classical left-handed (the internal bracing is not always symmetrical, so be careful if re-stringing) and anyone else's right-handed guitar I could borrow. Now I play fingerstyle acoustic and the "claws" mean I can't play righty guitars (or my better half's acoustic bass).

The duo I play in regularly get compliments about the two guitar necks pointing different ways.

BTW, Hendrix played a right-handed Strat strung upside down. Tried that in my youth and have the scars from the volume and tone pots on my inner forearm as a result of too-aggressive playing! Elizabeth Cotton really played a righty guitar upside-down - picking the bass lines with her ring and pinky fingers and the melody with thumb and index. Can anyone else do this?