Knowing how to compose and edit your portraits can be quite challenging whether in camera or in post processing / cropping the photo. Chopping off at the wrong place like the knees, the ears, or the joints might ruin your shot. Below is an illustration showing: in red the NO - technically wrong cropping places, and in green the YES - good cropping guides.
When it comes to the headshot, crop in tight along the sides of the face, and cut off the image a little below the end of the hairline, and just below the chins.
As for the legs, well crop just above the knees or take the whole thing including the shoes!
First understand the rules of photography, then break them as part of your creative journey.