Portrait lighting styles

Generally, when do you use even lighting across a person for a portrait vs. varying the light to draw emphasis with the light? Are photos with even lighting across the portrait considered boring/bland vs. while photos with varied light artistic?

Thanks.

How dramatic the lighting is based on the mood of the portrait you are trying to achieve.

Flat lighting doesn't need to be bland. Tonality can be enhanced by using different modifiers.

Flat lighting, at least in my opinion, works well for high key.

The modeling created by the lighting placement can look contrived if not done correctly.

What are you intending on shooting?

So much depends on the subject, the shape of their face, whether you want drama, or you are trying to emphasize beauty.

I think portraits look best when using close-proximity light placement to elicit some natural fall-off. Light fall-off helps create subtle gradients of light-to-dark, which helps create form. I generally place my key light as close as possible to my subject, both to increase wrap, and to enhance light fall-off. As I've said before, I think many of those starting out in portrait lighting often suffer from too much fill, rendering a flat, shapeless form. Also, as Gonzo mentions, face shape often influences how the subject looks under any given lighting approach, so no single rule or technique applies to every face.

it depends on your client. I shoot 40 portraits a day and usually what everybody wants is to look good (no doubt about that). You should know when to hide imperfections by lighting, if it fails, then you resort to posing and shooting at different angles. At the studio we do flat lighting for green screen like photo booths and the likes ... where light ratio is not really important.