I am amazed that most of my model portrait shoots are pretty much unscripted. I often get a chill thinking to myself "what in the heck am I going to do?" Knowing your location often helps, it makes it easier to place someone into the scene if you've used or visited it in the past.
The one thing that I know is if I don't like the existing lighting situation I will not hesitate to whip out a few speedlights to make everything Mo better.
Sometimes you think you've nailed it and sometimes you miss by a country mile. Take this image from this week's shoot was a foul tip -
The beautiful thing about shooting RAW is that you have about 4 stops of control (plus or minus) which comes in handy when your creativity is working overtime. The more shots I take, the more I learn.
Even though there are loads of technical ways to light a subject including using a hand held light meter, measuring the distance from the camera and the subject and dividing that by the guide number or using the fstop and dividing that into the guide number... I am confused but the one thing that works for me is to try to see the light. Try to view the scene through your viewfinder, set the fstop and the shutter speed and then pop your lights on full. In most cases the light from the flash overwhelms the shot. From that point on it's duck soup to find the right set point that will give you a nice balance between the ambient light, from the setting sun and the fill from your flash. I'm sure that anyone who really knows flash photography is going to read this and say "he'd better hit the books again". I will and hopefully I'm not too far off.
Use the force Luke...