1) Don't just read your notes over and over
Reading your notes for the first time allows you to extract a lot of understanding. However, the third or fourth time onwards when you read them, it gives you a sense of illusion that you know the content. This makes you miss out on the gaps between the content that is crucial.
2) Ask yourself questions when you study
Pretend that you are a teacher and teaching yourself. Ask yourself questions so you can understand the content really deeply.
3) Draw out if you are a visual person or use flashcards
Create mind maps and visual diagrams if you feel that diagrams can help you understand and summarise a whole chapter.
4) Dont cram and leave everything to last minute
As the usual saying goes, discipline and consistency makes you end at the top.