Not a leftie, but this is a common theme in FP communities. Loads of videos on YouTube, for example this [1] is one of multiple videos from Goulet on this subject.

[1]: https://www.youtube.com/watch?v=i3sAngid8aI

There's several points but iirc the other main point of focus is getting an ink/pen/paper combination that gets ink dried asap. But that's quite finnicky and you can't just start writing on any random document…

Honestly, if you've been traumatized by a fountain pen as a leftie, maybe don't force yourself through this again, but for many lefties it seems to be going great!

I’m a lefty. Been using fountain pens exclusively for years. Find a quick drying ink and paper. I love Kon Peki (great blue that dries fast enough for me to write). And don’t worry about having ink on your hands. You look like an artist.

“Proper” writing technique has the pen being right angled to the line, which puts the wrist below the line and avoids smudging. It’s pretty uncomfortable at first, but can be learned.