This picture is another one of a location business shoot primarily for the purpose of headshots and website use.  I placed another one from the session in Recent Favorites and the concept of setting up this picture are the same with a slight variation of placement of lighting.  

One thing about on location portraits is the highly variable character and quality of light.  For this particular picture, I decided to position the client in front of a window so the outside buildings would be visible.  As usual, I set my shutter speed to the maximum sync speed (1/250), set my aperture (f4) and ISO (400)  to obtain a slightly over exposed background (about 1/2 to 1 stop over) and then filled her face with a strobe (SB900 controlled with a miniTT1/AC3 and Flex5 from PocketWizard).  If memory serves me correctly I used a manual setting to adjust the strobe based on what I was seeing on the camera screen (chimping).  I was also sending the strobe through an umbrella.  In an earlier pictures, the light was a bit flatter so I moved the strobe further to my left to generate a bit more short lighting. 

By setting the shutter speed first (at 1/250) I am able to reduce the background light to the maximum possible extent relative to the front lighting (I could use hypersync technologies to use a faster shutter speed, but that did not seem necessary for this picture) and still not reduce the efficacy of the strobe lighting.  I also wanted a bit of a depth of field (hence f4 vs something lower) and then I adjusted ISO to get to the exposure I wanted.