Retrieval practice is simple to describe and easy to do badly. The core loop has four steps: study the material once, close it, produce answers from memory, then check them against the source. The closing step is the one most often skipped, and it is the one that matters — the benefit comes from the effort of recall, not from exposure to questions. If the material is still open in front of you, you are rereading, not testing.
A workable schedule follows the spacing research: a first self-test on the day of study, a second after two or three days, a third after a week, and further retests at widening intervals for material that must survive months. Mixing topics within a session — interleaving — feels harder and scores lower in the moment, yet reliably improves later performance. Keep a record of which items fail repeatedly; those are the ones the forgetting curve is winning, and they deserve the next session's attention.