The spacing effect
Reviewing material over several days, with gaps in between, leads to better long-term memory than the same total time crammed into one session.
A simple schedule
Review new material the next day, again after about three days, then after a week. Each review is short: ten to fifteen minutes of recall.
Mix topics
During practice, mixing different types of problems (instead of twenty of the same kind in a row) helps you learn to choose the right method, which is what tests ask for.
Do this today
Pick one topic from this week and put three short reviews on your calendar: tomorrow, in three days and in a week.