The rule of thirds is a type of composition in which an image is divided evenly into thirds, both horizontally and vertically, and the subject of the image is placed at the intersection of those dividing lines, or along one of the lines itself. https://www.slrlounge.com/glossary/rule-of-thirds-definition/
My example using rule of thirds:
Best and Worst:
BEST
This is my best image because it uses the skill of rule of thirds quite well and also has the image in a shallow depth of field.
WORST
This is my worst image because it doesn't have the rule of thirds.