With a majority of my portrait work I use just a single speedlight and one of my traveller8 Softboxes. This portrait of well-known Australian actress Virginia Hey was no exception (you've seen Virginia in countless movies and TV shows, including Mad Max 2 and Farscape).
You can see by the placement of the softbox to Virginia's face I kept in close (about 3 feet) and above her eyes to give subtle shadowing under her nose. I also added a 1/4 CTO Filter to the speedlight to give a slightly warm tone to her face, and in this case the gray seamless background paper. You can see the difference in color temperature between the 2 pictures- another great example of how a very slight color change can really give you completely different looks. Many times I'll shoot against a plain white wall and vary the look with color filters or exposure.