I just started using AE Lock in Av mode recently and I need to know where do you meter it at? for example for portraits, do you meter it at people's eye/skin/etc? for birds with colorful feathers, do you meter it at the brightest/darkest feather? is there any generalization on where one should properly meter before pressing the AE Lock? I've tried googling and reading the manual about this but couldn't find any information about it (or maybe I missed it).
and when using AE Lock, is it more advisable to use Spot Metering instead of Partial Metering?
here's a sample of a picture I shot in Av mode and used AE Lock with Spot Metering. I focused on the duck, then locked the exposure at the brightest feather of the duck and recomposed. Did I do it right? or was method wrong?