Handwriting education is sorely lacking for left-handed people. Most often they are left to figure out things for themselves.
Things you -- or other left-handed people -- could try:
- Rotate your writing surface. The more you rotate your writing surface the more it changes the writing direction from left-to-right to top-to-bottom which solves a lot common issues. It may take some getting used to but it's a lot better than using a claw grip to bend your wrist out of the way of your writing.
- There are "left-handed-inks" for fountain pens available these days. They generally dry quickly and resist smudging. Combine this with a pen that has a round tip: it won't give a hoot about which direction you're applying force in since it won't dig into the paper like a square or chisel tip will.
- Use a calligraphers grip. Place the pen in your hand, the body of the pen resting in the web between your index finger and thumb. Rest the grip of the pen on your middle finger in a comfortable spot, some people rest it on the side of the fingertip but moving it up till past the knuckle places it in an area with more padding. This does necessitate rotating your paper to avoid smudging but it does make applying less force to your pen a lot easier. If you still have pressure problems with this grip you can try modifying it by resting the pen on your index finger instead and holding it with your thumb.
- I'd consider this somewhat of a last resort since it's not quite the best writing technique but you can try holding the pen some ways above the grip. The extra distance from your writing can be just enough to avoid smudging.
The world sure isn't built for left handed people, but it seems to me that a lot of suffering could be avoided by including specifics for lefties in writing education.