read the textbook, reread the textbook, make sure you know all the terms - you dont need skill, just a good memory. + practice diagrams, they love asking for diagrams.
Learn your terms but more importantly, learn how to develop a believable answer which could potentially be a real solution to a real problem.
Whilst it's great to read the book and memorise all the definitions, the reality is- a lot of it in the exam will be your ability to apply it to a situation. The definitions only cover you for the multiple choice questions!