If your lighting is controlled and the background is already set, the best approach is usually to shoot in manual exposure and confirm with test shots and the histogram. That avoids the meter being influenced by the bright background at all.

If you do want to use a metering mode, the key factor is how much brighter the background is than the subject:

• If the background is much brighter, spot or center-weighted metering is usually safer than matrix/evaluative because they give more priority to the subject.
• Spot metering works well if you have a specific tone on the subject to meter from.
• Center-weighted can be better if the subject has a wider range of tones and you want a more balanced reading.
• Matrix/evaluative may still work if your camera is good at recognizing a bright background, but it is less predictable in this setup.

In a studio-style portrait setup, manual exposure plus histogram checking is generally the most reliable choice.