My favorite pins are available from Clotilde or some shops. They are called IBC Glass Head Silk Pins 1 3/8" Sharp. Super Fine .50mm Steel Shaft 250/box.
They are amazingly thin, very sharp and slide in the fabric with almost no distortion. You can sew over them, altho if you hit one, it will bend into a U shape! Even with hard use, they bend. I keep them in their own pincushion and try to be gentle with them. They are the best pins I have ever used!
And, yes, they are expensive but I am worth it! Retail is about $7-8 per box. I buy a new box every year or two, so I really don't think that is too much to spend.