Central to writing a good case note is developing your ability to distil the key facts and ratio decidendi and capture all of this in a few handy, easily memorised bullet points. Simple in description but maddening in practice, especially when some cases span hundreds of pages.
Much of your ability to sift the vital points of law and facts from broad historical outlines of the law or seemingly irrelevant segues will come from mastering your bulk reading skills and constant practice.
Once you have read a case and feel you have a grasp of some of its major issues, you will need to organise them as a case note.
 http://survivelaw.com/index.php/blogs/study/348-how-to-write-a-case-note