Reminds me of the quote, “There is a crack in everything, that is how the light gets in.” LC
As to placement you would have to consider job opportunities, clothes, pain, if you want to see it, if you want others to see it, how often you want others to see it. Also worth considering is what prompted the quote. For example I wanted an organic plant like phoenix on my right shoulder blade and down my back. I had wanted it prior too but was unsure of placement, but after I injured and healed that part of my body it made more sense to put it there. Also It could be covered.
I like the idea for dirt and feet or ankles.
Your feet are not just closest to the ground but you are grounded by them and can “plant” yourself with them.
The other benefit is they can be hidden for formal or business, or flashed for casual. Another perk is lack or warping due to weight gain. But given the amount of bone in that area very painful.