I learned about this as an adult and felt like such an idiot for going through school without learning the trick. And maybe a little mad at my third grade teacher.

Paper at a 45 degree angle + hand below the line I'm writing be works like a charm.

My introduction to rollerball pens forced me to learn how to do this, otherwise, I was smearing everything I had written. I did some research and found out that curling my hand around the pen was the wrong way to hold it.