Not a bad cut @Pablo Garrido Suárez, but the chin is cut too far from the bottom of the canvas. 250x250 is not an enormous canvas so ‘wasting’ 10-15 pixels in height of it on the neck isn't the best idea; it is recommended that you leave no more than 2-3 pixels of empty space above the top of the head and beneath the chin and/or facial hair.

In some sources like this one, the person in the image may have a longer neck than usual, this would be quite difficult to achieve naturally. This video displays a simple technique of how to cut close to the chin and still display a bit of the collar:

Can we have the original source for it so that we can recut it accordingly?

I imagined that could happen, but my knowledge of graphics is not enough for much more.

I leave the source of the original image: