I have a real difficulty with 1/3rds. I practice on one of my grandsons, he was a good sport with helping out with this assignment.
I find myself not leaving enought wiggle room, as I call it, around the person I am photographing.
I am trying to remind myself when photographing people
1. get the lighting right
2. set the right aperture
3. keep shutter speed above 1/60 or 1/200 for kids
4. focus on the eyes
5. keep the eyes on one of the 1/3 intersecting lines
6. don't crop off limbs
This is a work in progress and is easier said then done.
f/3.5@1/00 ISO 250 50mm withbounced flash