It’s only been in the last few years that I have begun using electronic flash when shooting outdoors. What I have found is that I prefer the fill flash function on my flash unit (the aperture and shutter speed are adjusted to correctly expose the background, and the flash is fired to lighten the foreground, usually my subject). The use of fill flash also enables me to obtain much sharper, crisper shots, along with that desirable catch light in my subject’s eyes..Rarely will I ever use my flash at full power. I will typically power it down, depending on the amount of ambient light available, anywhere from ½ stop to 3 stops. I never use as my main light source when shooting outdoors, as this causes my subject to look like I used a flash, and that is not my goal. I want my subject to look and feel natural.
A very useful gadget which fits on the face of the flash unit, called a diffuser, is a must have accessory. It’s a white plastic object which diffuses and spreads the light across a wider area.
An interesting fact to remember is that the strength of the flash output is not determined by your choice of shutter speed, but by your choice of aperture. I consider the electronic flash to be a critical piece of equipment. I highly recommend that you learn how to use it for any critical work. It can make all the difference.