1. Write notes from my class notes, summarising them and ensuring I understand them fully.
2. (Only for particular subjects) I make mind maps of topics, or timelines.
3. Flash cards! One side question and the other side the answer. Particularly good for history!
4. Past papers. They let me know what I need to focus on primarily.
5. (Sometimes) I stick sticky notes around my house/bedroom, usually with processes, quotes, or definitions on them.
I guess I start quite early but learn everything quite thoroughly.