Working with flash outdoors is more popular now than ever. And there are a few different ways you can make your images appear by simply understanding the controls that are available to you. Consider the background as a highly important aspect of the picture and look at how it's brightness affects the image.
Here is an example where the background and the subject are in balance and while the flash is subtle, it is very clearly used in order to enhance this beautiful face. A medium sized softbox gives the soft light required to make the image not look too "flashy."
Another example of the natural balance of the two, ambient light and flash. What is important in this image is the fact that the light direction of the ambience on her face is also where the softbox with flash came from in order to look natural.
With the simple increase of the shutter speed, the soft, natural look of the flash/ambient combination goes away in favor of a more clear "Main Light." This look was achieved by using "high speed sync" mode on my Canon 600EX speedlight and setting my shutter speed up to 1/1000th of a second.
Here is a fun example of making the flash appear as sunlight coming in a window on this movie set. A slight warming gel on the flash and high speed shutter results in this great example of "what you see is NOT what you get.
Getting time to test and practice with your speedlights in really important in order to learn these techniques. From shutter speed to light shaping tools, to understanding the advanced menus in the flash units of today, all are elements that combine to give us a look, mood and feel of our work and it takes practice and study time to learn to do this work effortlessly.