I’ve played guitar left-handed for over two decades. Every diagram, tutorial and scale chart out there is drawn for a right-handed player, so you spend half your practice time flipping things around in your head.
That frustration is why I built SouthpawStrings.com. Its tools show the left-handed fretboard by default, not as an option hidden in the settings. Right-handed players are welcome too. Everything works just as well the other way round.