Tracing
Follow the pieces from the buffer, breaking into a new cycle when one closes.
Tracing cycles
Start at the buffer. Look at the sticker in the buffer's top spot and find where it belongs: that spot's letter is the first target. Then look at the piece in that spot and find where it belongs: the next target. Continue until the next target would be the buffer piece itself: the cycle is closed. If pieces are still unsolved, break into one of them (the first in letter order is a common rule): memorise its letter, follow from there, and memorise its letter again when the cycle returns to it. Pieces in their place but turned (twisted corners, flipped edges) are noted separately.
The memo trainer, on the Learn page, draws a scramble with its letters and traces it for you, kind by kind, so you can check your own tracing.