Fine hair gets blamed for a lot of styling problems that aren't actually about the hair. I hear it constantly: "my hair just won't hold anything." Most of the time, the hair is fine. The tool is wrong.
Fine hair has less surface texture for a pin or clip to grip onto, which means it slips out of styles that would hold fine on thicker hair. The instinct is usually to add more product, more pins, more hold spray. What actually helps is the opposite: fewer, better-placed tools.
A hair pin built for fine hair needs to be sized correctly. A large pin in a small amount of hair doesn't have enough hair to grip, so it sits loosely and works its way out. This is where the Petite Power Pin does its best work. It's sized for fine to medium hair specifically, which means it seats properly instead of floating on top of a style that's too light to hold it in place.
A few things that make a real difference with fine hair specifically. Add texture before you pin. Freshly washed, very smooth hair is the hardest texture to hold. A light texturizing spray at the roots gives the pin something to catch. Use a smaller pin sized to your hair, not a larger one you're hoping will compensate for slipperiness. Keep the prongs close together when you insert it. Wide-open prongs have less tension, and tension is what keeps a pin seated. Weave rather than slide. Pass the pin through, catch a small section near the scalp, then bring it back through. That locking motion matters even more in fine hair, where a straight-through pin has almost nothing to hold onto.
A French hair pin sized correctly for fine hair does more work here than people expect. It's not about strength, it's about fit. The right amount of pin for the amount of hair you actually have.
For fine to medium hair, the Petite Power Pin is the one I recommend most. It's built specifically for this, real hold without overwhelming a lighter amount of hair.