I like #13 ~15, as I know that

when shooting portraits outdoor, the simpler the backgroud, the stronger your portrait will be. so you can throw the background out of focus by using an aperture like f/2.8 or f/4.
Althought there's plenty of light for shooting portraits outdoors in the middle of the day, most of that light is very direct and will wind up casting hard, unflattering shadows on your subject's face. so move subject into the shade, where the light is softer, and the shadows are less prominet and much softer. don't move into a cave-just move to a shady area near the direct sunlight.
It is my personal opinion.