If you're new to flash photography, or want to try it outside and off-camera, there are a few things to keep in mind. This behind-the-scenes video is a good introduction on how to get started.
For the first couple of years of owning a dedicated, interchangeable lens camera, I was convinced I loved natural light. I wasn't wrong per se, but I also wasn't entirely right. I thought that flash photography, particularly when it was conducted outdoors, looked dated and generally not the aesthetic I enjoy. Eventually, I tried it for myself and I proved my suspicions correct. This was not because I was correct, however.
The mistake I was making was simply not understanding how light works and how to properly control it. The shots I wanted to take certainly benefited from an off-camera flash, but I didn't know how to balance the light. It is one of the trickiest elements of flash photography, but if you want to shoot outside, it is arguably the most important consideration outside of proper exposure. My general advice would be to not overcook it with high flash power, particularly if the natural, available light is to play a role in the final image.
In this video, Jiggie Alejandrino talks you through a portrait shoot of his that was shot outdoors and with one single flash.