I am not an expert in puncetto. I was taught the technique and have used it for decades, but have studied very little about its history. It is a functional art for me, not a textbook specialty.
Forming the basic stitch in puncetto. It is like the embroidery "blanket stitch", but the needle goes behind the thread instead of in front of it, and it is looped so that pulling the thread forms a knot. In this example I am stitching from left to right, but the stitch remains the same regardless of direction, just reversed.
It is usually worked free-hand in back and forth rows, but it can be worked as shown, starting as an edging, and is easy to work in the round. I've seen some lovely pictures of girls with puncetto as a sleeve edging. This is really the only stitch, the only variation that I have ever seen made 2 loops in the knot instead of one.
Pulling the stitch tight while placing it where you want it.
Snugging it tight.
Forming a vandyke point by decreasing a stitch each row, and working back and forth.
Also showing an arch. It is very easy to do a mesh like Irish Crochet Net, or like filet crochet. Although I have been working very loosely in these images, it is also possible to place the stitches very close to each other, making a fairly solid fabric.