Like any sex or kink toy, material choice matters. So if you’re using wooden clothes pins just know they’re one time use only — the wood is too porous to be sanitized.
Another good choice is to use a toy that doubles as nipple clamps — either the stand alone style or the kind that are attached by a chain.
When experimenting with clamps, get familiar with your tool of choice before it touches any sensitive part of your body. Some clamps are adjustable and some aren’t. Try them out on the pad of your hand, first, to see how intense the pressure is. Also, consider the different sensations between metal clamps and clamps that have a silicone or plastic coating.
Keep in mind that clamps can cut off blood flow or cause damage, so be mindful of time when playing and don’t leave them on too long. Especially if you go numb while wearing them, you may forget how long they’ve been in place. But this will come back to bite you because they generally hurt a lot more when they’re coming off then they did going on! That’s because the tissue has become extra sensitive, plus the blood is flowing back into the area (like the pins and needles you get when your foot has fallen asleep.) So start with short periods and work your way up — cautiously.
For folks with vulvas, the outer labia are a good place to start when playing with clamps. Again, be sure to place them cautiously, keep an eye on how long they’re in place, and then remove them just as carefully. Open the clamp to take it off...don't pull!