How to hold

It's only been a year since I shifted from ballpoints to fountain pens. The problem is, I can't hold it lightly, I always grip the section tightly (of course not tight enough to spring the nib). After a few pages, my fingers almost choke. I tried holding it very lightly so the pen writes on its own but after a few lines I involuntarily grip it tightly.

Are there any tips to hold the pen lightly and let it write on its own for people like me?

TIA!