What is a good first step when approaching a fitting-parts problem with several pieces?

A good first step in a fitting-parts problem is to identify the most distinctive or unusually shaped piece — one with a unique notch, angle, or outline — and figure out where it must fit in the assembled figure. Because that piece can only go in one place, it anchors your reasoning and quickly rules out answer choices that place it wrong or alter it. From there, you build around it, matching the remaining pieces by their edges. Starting with the most recognizable piece is more efficient than trying every piece at once and is a reliable visualization strategy on this subtest.