Most important is the quality of the pins. You want a pin that is nicely polished, with a perfect point. Japan, England, and Switzerland are known for producing top of the line pins and needles. Some US companies subcontract to other firms abroad, but most of the time the quality control is good. I've listed some of my favorites and their intended (or adopted) purposes.
My favorite all around pin is the glass head pin from Dritz. I sew with silk and wool more than anything else, and the fine polish of the point on this pin is always reliable...won't snag your delicate fabrics. The white glass head allows you to leave the pins in place while you press (although I don't press directly over them because I don't want an imprint on my fabric)...they won't melt (don't ever try that with a plastic head pin!). They are also easy to find once-uh-dropped onto the carpet. (bottom right)
Clover also makes a very good transparent glass head pin...even better for more delicate fabrics. The Clover pins are longer and they will bend if you try to use them in heavier fabric. (top right in the picture below)
Iris-Swiss pins are favored by professional dressmakers. This all-metal product is affiliated with Schmetz. These very fine pins do no easily bend, and have a very fine head. They are perfect for sewing with all types of natural and synthetic fabrics. (not shown here, they come in an orange box).
When I want to pin a larger piece with straight edges, I opt for the Dritz quilting pins (with the yellow plastic head). These are also a very good quality, suitable to pin cottons, woolens, and stiffer fabrics. (center bottom)
Discard dull, discolored, or bent pins, and enjoy sewing with some delightful new pins! Like a good pair of shears, they make the sewing process that much smoother and easier!
