I'm not really offering advice on how to remember cases because everyone remembers them in different ways, but I will offer you one piece of advice, if you can't remember the case name but know the facts and the way it influenced/changed the law then write about it but just call it a 'decided case'. I went into an exam last year for my degree and forgot quite a few case names, but because i remembered the principles that came from the case and wrote about them I came out with only a couple of marks off a 1st.