Hi rebecca, Check out the studyclix blog http://www.studyclix.ie/Blog where you will find a blog post called "How to study for your junior or leaving cert exams". Best of luck.
1) Writing out things. Try do it in short bullet points but in a way that you will understand what you are talking about.
2) Saying things. I find it works if you say things they stick in your head.
3) Read, underline and write.
4) Mind maps :D
Hope this helps. x