The one part of gaokao preparation that really is a memorisation problem is vocabulary: the 3,500 core English words and the list of classical Chinese function words. Both punish cramming and reward daily contact.
Any spaced-repetition system will do the job — 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 a day. Add fifty because you feel behind, and tomorrow's reviews will bury you; you will have abandoned the system by the end of the week.
For classical Chinese, do not memorise the character on its own. Memorise a short line from a canonical text that uses it in the sense you need. Meaning without context evaporates within a week.