Light is everything in photography, it doesn’t matter whether the source is natural or manmade, to take images for uniqueness understanding the light source is important.
This page is intended to help shed some light on the subject (Pun intended)
Your First Light Setup (in 3 steps) using a speedlight
Create Professional Studio Portraits using a Speedlight and an Umbrella
Five different Portraits with one light in a small studio, first shot in each portrait is in TTL to set the exposure than changed to manual
 Rich Photographer vs Poor Photographer
2 Portrait Lighting Setups For Men
Dramatic Portraits using a Beauty Dish with Joel Grimes
Shooting Portraits with One Speedlight
Dramatic One Light Set up
Backlit Portrait with just one light
One Light Headshot: Behind the Scenes with Sal Cincotta
Natural Lighting
Speed Lights & Stobes
Light Modifiers
One Light set-ups
High Speed Sync
Mixing Ambient light with Flash
Lighting Patterns