Let it Flare
This is a picture I made back when I was testing out Speedlite (small, battery-powered flashes) setups outside. An easy way to get away with the power limitation of those units is to shoot in a darker environment where you don't have the full power of the sun to deal with.
I found this spot in a park, late in the day, where the only light reaching through was the sun visible between trees. I had arranged to get to the location just in time to set up my lights before the sun would be at the correct height for the picture. To dim the ambient light further, I added a few stops of ND in front of my 50mm lens.
Setting up lights. I am using a large aperture (ƒ/2.0, 1/160th, ISO 100) to prevent the background
from stealing too much attention away from the subject.
I first placed the key light, which is a Canon Speedlite 580EX II in a shoot-through umbrella, to my left. To separate the subject from the dark, backlit trees, I added a kicker light (a 430EX II) farther to the right. I used a CTO gel to warm up that light for it to better convey a sunset ambiance.
The sun introduced quite a bit of flare, but that's a look that worked for me (and is not surprising to the viewer, considering the position of the sun). I tweaked the contrast and darkened the edges a bit in post-production to keep it under control.
Using Speedlites and umbrellas really makes it possible to work fast; all in all, we mustn't have been there more than 20 minutes!