For green-screen portraits, the key is control and separation. Light the green screen and the subject separately if possible. Aim for the screen to be evenly lit, and keep the subject far enough in front of it that they don’t cast shadows onto the background.

Flash or continuous light can work, but controlled lighting matters more than “natural” light. Indoor setup is usually easier than outdoors because you can keep the lighting consistent.

Watch for green spill: a large green background can reflect light back onto the subject and contaminate skin tones. To help with color, shoot RAW and set a custom white balance or use a gray card and correct white balance afterward.

Depth of field should be deep enough to keep the subject sharp; the main priority is not blur, but a clean, evenly lit background and a well-focused subject.

Most important things to avoid:

• uneven lighting on the green screen
• shadows on the screen
• green color cast on the subject
• subjects wearing green or similar colors

In short: evenly light the screen, light the subject separately, keep them off the background, and manage white balance carefully.