The one part of gaokao prep that is genuinely a memorization problem is vocabulary — the 3,500 core English words and the classical Chinese function-word list. Both punish cramming and reward daily contact.
Any spaced-repetition system will work: Anki, a paper Leitner box with five compartments, or index cards you shuffle through on the bus. The tool is not the point. The schedule is.
Add no more than twenty new items per day. If you add fifty because you feel behind, tomorrow's reviews will crush you and you will quit the system by the end of the week.
For classical Chinese, do not just memorize the character. Memorize a short line from a canonical text that uses it in the sense you care about. Meaning without context evaporates within a week.