I think I've read it somewhere but just like to confirm this:

When doing E-TTL flash, the flash metering is linked to the AF points right? So the metering will only take into account the small areas covered by the AF pt(s)?

Sometimes I mistakenly AFed on a white shirt worn by the subject, and not only the face is not in focus, the pic gets underexposed as well.

I hope to set the habit that for taking flash shots of human subjects, select centre AF point, use partial metering circle on subject's face and do FEL, half shutter, then recompose and fire off. Is this a good way of getting well-expose shots, or are there better methods?

Please enlighten, thanks!