Today it is largely done as a Counted Thread Technique but in the past (as even now) some do it as a classic embroidery technique, that is with traced designs on the fabric to be executed not by counting ground threads.
Going through the museums all over Italy I found extant pieces of this technique dating back quite far. There are pieces of fabric with Punto Antico elements on them dating back to the late 15th century. The pieces are quite complex suggesting that the technique goes much farther back in time.
This is some work at the Collezioni Comunali d'Arte in Bologna:
Ancient pieces have almost the whole surface of the fabric covered in stitching while modern pieces are quite sparse in comparison though done with no less good taste. I like the texture, the bas-relief effect, it seems to me like carved marble. The openwork spaces balance the textured areas using chiaroscuro effects so that this mainly monotone embroidery does not suffer in the least for lack of colour. The curlicues are my favourite element.
Another piece from the Collezioni Comunali d'Arte in Bologna:
This is some work exhibited at the Palazzo Davanzati in Florence:
As with any embroidery technique, there are a number of ways to execute the stitches. Taking the curlicue (Punto Riccio) as an example: it is executed in three parts with a base of Double Running Stitch (or Stem Stitch or Cable Stitch or Back Stitch) which are then whipped with an Overcast Stitch for each base stitch and then the whole line is covered in Overcast Stitches done side-by-side to create a wonderful raised stitch. Time consuming? Yes! Worth the effort? Very much so! It takes a bit of practice..
My first ones were quite lumpy but after many attempts, they are pretty smooth now...
Here's what they look like over Stem Stitch with only one Overcast Stitch per Stem Stitch (overcast the overlap) ... This gives quite a different effect which is nice too.
Anyway, its a fun stitch to play around with, giving your work some texture.
There are some Punto Antico online tutorials at Tuttoricamo under the "How it's Done" section (Antique Stitch). While you're there you can download some old books on the subject from the "Books" section: look under 'downloadable Antique books' - L. Vannini, there are three there.
I did a couple of articles for Piecework which are available for download from their website.
For some modern books:
Associazione Il Punto Antico (all books are either in Italian/English or come with English inserts upon request).
Tombolo Disegni (click "books", "libri ricamo", "ricamo italiani" - you need to send an email request to order) There you will also find a book called Punto Antico disegnato which is not a counted thread technique book but rather designs for traditional freestyle or non-counted thread, Punto Antico embroidery.
Most of the Carmela Testa books at Iva Rose also have some elements of Punto Antico in them though the instructions are a bit vague.
Check out YouTube as there are some tutorial films there too!