Here is a goal: How can I get a good photo of a stranger, when they ask you to take their pic?

Which way makes more sense to accomplish this goal?

Available options:
-Take a few pics candidly while they get ready for their pose, sometimes the candid shots turn out best..
-Take a few calls candidly while they get ready for their pose, sometimes the candid shots turn out best..
Take a few pics candidly while they get ready for their pose, sometimes the candid shots turn out best.