Ponchos were very fashionable when I was teenager (twenty years ago) but I did not get it. Now they are again in and I decided to knit one. I bought two shadows of same yarn in my favourite e-shop (sorry, only in Czech).
I cast on 195 stitches and knitted four rows knitwise to make non rolling border. Then I started to make holes in two rows. In first row I did three stitches knitwise, then five stitches cast off. I repeated till the end of row. Next row: purlwise three stitches, then five stitches cast on. The number of stitches ought to be still same.
Futher it was more simple: only stockinette (odd rows knitwise, even rows purlwise). At the start of each row I join knit together two stitches into one because I want to form triangle. I finished when I see it could be narrow enough for neck and last several rows were made in moss stitch.
I made four triangles and joined them together. In front I left poncho open with strings.