It's not easy to get soft directional light outdoors in daylight, and arguably it's even harder for candid shots without setup. One solution is to bounce an on-camera flash into a reflector.
In the shot above, I got soft directional light in daylight by bouncing an on-camera flash (gelled with 1/4 CTO) into a handheld Lastolite 5-in-1 Mini 18" Trigrip reflector (using the white-surfaced reflector). The area was shaded, so it would have been possible to take a shot using just existing light, but not without blowing out the background (i.e. in the shot above, the flash brightened the subject and thus reduced the contrast between the bright background and the subject):
The soft directional light also makes the subject look more three-dimensional than in the image shot purely in existing light. Finally, with the flash, it was possible to use a faster shutter speed and/or lower ISO than with the existing light only.
COMPARED TO HANDHELD UMBRELLA
I think it's much easier to use a handheld umbrella because the reflector solution requires positioning the flash properly (a pain when switching between landscape and portrait shots) and requires more careful aiming of the flash and the reflector. IMHO, the umbrella is also less conspicuous and thus more spouse-friendly. On the other hand, sometimes all you want is a reflector (e.g. when you're shooting a video), which the umbrella can't be used for. The reflector solution also allows you to switch to using the flash on-camera.
A cautionary note when using reflectors: sometimes, a subject can look fatter with a reflector, when the reflector is aimed upward (e.g. to brighten the eyes) but fills in too much of the shadow under the subject's jaw. Not good. Gather a sample pic of this at your own risk!