Commenting with the others: I'm a left-handed writer and an avid fountain pen user. It isn't so bad.
The best thing I can say is: try to learn to write under the line (under-hand) as opposed to hookwriting or sidewriting. Those make things pretty tough. If not, there are things you can try: Prefer extra-fine (EF) or fine (F) nibbed pens. Private Reserve and Noodler's make some fast-drying ink. This combo will often allow the ink to dry faster than your hand can get to it.
The best thing I can say is: try to learn to write under the line (under-hand) as opposed to hookwriting or sidewriting. Those make things pretty tough. If not, there are things you can try: Prefer extra-fine (EF) or fine (F) nibbed pens. Private Reserve and Noodler's make some fast-drying ink. This combo will often allow the ink to dry faster than your hand can get to it.