Understand what type of learner you are using the VARK model (visual, audible, reading/writing, kinaesthetic) and find ways to take advantage of that. For example, if you're an audible learner it would help to listen to pre-recorded lectures or an audiobook on the topic you're learning about, if you learn more through reading and writing then it would help to spend time reading from different learning materials and taking concise notes.
Relate information back to something that you don't need to actively think about. For instance, if I'm doing Chemistry and trying to learn about the structure of the atom, I think about the solar system. Now, every time I come across a question regarding the atom I just need to say "solar system" to myself in my head and I'll be able to remember.
For memorisation, try writing down a few of the phrases or keywords that you need to learn 10 times each with a reference next to you. After a 5-10 minute break, see how well you can remember without the reference. You'll find that with a little repetition the information sticks much better and you'll have no problem in an exam when you're required recall definitions, dates, phrases etc.
After answering the questions in the book on a particular topic, try doing exam style questions. There are plenty of resources online where you can find question sheets from previous exams for a specific chapter to really test yourself!
Focus on your exam technique! When doing exam style questions, try using the mark scheme and mark the questions yourself. This will give you the opportunity to see exactly what the examiners want you to write and how to display the information. If you do enough, you'll start to learn the pattern and how to word answers to get maximum marks!