To help you out, below I have written about a few different portrait lighting techniques and when it is appropriate to use them.
This style of lighting is exactly as it sounds – it splits the face equally in half with one side of the subject being lit and the other in the shadows. The light source is shone at a 90-degree angle directly onto one side of the subject's face, to get this effect.
Lighting a subject this way can be used for creating dramatic portraits for people such as musicians and artists.
The aim of this lighting is to make the model appear unflattering and slightly creepy under a single light.
To achieve horror lighting, the light is placed directly above the subject to catch the shadows of their facial features. The light catches only on their prominent features, like their cheekbones and nose, leaving their eyes and mouth covered in shadows helping to create a dramatic and dark image.
Rembrandt Lighting is named after the famous artist of the same name, due to his distinct pattern of light in his paintings. This form of lighting can easily be distinguished by the triangle of light under the eye of the subject.
To achieve this style of lighting, the subject must be slightly turned away from the source of light be it a window or studio light, preferably slightly above them. This will help to create a more defined triangle of light and bring out the shadows adding more depth to the image.
The thing to remember with Rembrandt lighting is that not every model is appropriate for this form of lighting, due to the structure of their face. If the bridge of their nose is too flat, then the triangle of light might not be so prominent and difficult to make out.
Experiment with different lighting effects and see what works best for your subject. In the end, practice makes perfect so nailing each effect and many others, will take some time and persistence.