A great way to learn how to light with off camera strobes is to study the catchlights in the eyes of other images. If the light hits the eyes in anyway then it will reflect off the eyes into the camera. Once you get the idea of where the light sources are coming from you then study the face and see the results of the lighting. Once you get good at reverse engineering the lighting you can tell just by looking at the face where the main lights are coming from.
In the past when reverse engineering (learning) lighting setups in fashion magazines, I found most of the images were taken with a single strobe and maybe a few with a reflector underneath. Some were shot with a ring light or beauty dish as well as a single strobe. But a lot were shot with just a single light source.
Light coming from the front creates less shadows across the face and hides blemishes since the light is front on and even across the face filling the dimples and bottom of the creases. It also hides the size of the nose as there is no shadow to judge how large it is and usually the camera angle is front on also so there is less of a profile of the nose.
As you move the light more to the side less of that light gets into the creases and crevices of the face and shadows start to form emphasizing the wrinkles. Light that is broadside to the face will create the most shadows across the face.
Another factor in lighting anything is the size of the light source. Take a look at some of the catchlights and see how much of the eye they fill. If they fill a good portion of it then either the light source was very large or very close to the face. A benefit to using smaller light sources is when they are placed closer to the subject less power is needed to produce the same lighting effect as a larger light source further away. This also means there will be less cycle time (flash recharge) between shots so you can shoot faster and get more images in a given time. One other benefit to using smaller light sources closer to the subject is the light will be further away from the walls of the room and along with the reduced power will greatly decrease undesired bounced light. So big powerful light sources with big light modifiers are not required to create well lit photos.
This phenomenon is called relative light size, where the light source size is relative to the subject size. Shooting a full size car? You are going to need a huge light source or many light sources to produce smooth lighting. Shooting a model car or toy car? The light source is many times smaller to get the same quality of light. Shooting a full length portrait as compared to a headshot? The light size will have to be much larger to produce equal quality of light. The larger the light source more of the light will be from angles wider than the center of the light source. This wider light hits the subject at broader angles to the main axis which softens the boundary between light and shadow seemingly wrapping around and tapering off rather than abruptly stopping and creating a sharp boundary.
Speaking of light source sizes, the Sun, is 100 times larger than the earth. It's a huge and very bright light source. But it is so far away from the earth that it's relative size is very small and produces what is called harsh lighting. That is why the Sun does not make great quality light since there is very little wrapped light and there is a very pronounced boundary between light and shadow. Morning or evening light when the Sun is low in the horizon produces a softer light and warmer colors as well. But to get great soft wrapped light using only sunlight you should take your subject into a large shaded area like the north side of a building that has reflected sunlight off the buildings across the street. Your light source is now the size of the adjacent building instead of the pinpoint that the Sun was. It is also less powerful which allows you to open your aperture a bit more for some depth of field separation.
Back to studying magazine photos. Study the shape of the light source. Is it round? Are the ribs of the umbrella visible? If so you know for sure an umbrella was used and was pretty close to the subject for eye to reflect the ribs. The closer the light the less power is needed and the catchlights are less blown out in the eyes revealing more detail. Is the catchlight rectangle and no details visible? Then probably a softbox was used. Is the catchlight at the bottom of the eye or opposite side of the main light and really dim? This is probably a reflector used to throw a little bit of reflected light back to fill in the shadows.
I will mention that in the few images where there were two strobes used in the image, the second strobe was to the side and behind the subject creating a rim light effect for separation from the background. This is not needed most of the time if the subject contrasts well with the background.
So armed with only a single strobe and maybe a simple piece of white cardstock for reflected fill you can create the same lighting on the stunning images seen in fashion magazines (minus the Photoshop touch-ups).
The next article on strobe photography will be using a single Pentax Wireless P-TTL strobe to create fashion magazine shots.
Until then, a little home work, grab some magazines off the checkout counter when standing in line at the grocery store and study the lighting used in the photo. Google image search some fashion magazine covers and study those. You will find in most cases the light source is a single strobe out in front and maybe some reflected fill.