Mental Heath is a totally different class that Pysch.  It's all about being theraputic and the different types of disorders.  I did very well in Mental Health and when I did my clinicals at the end the instructor told me I would never make a Mental Health nurse because I want to heal people and you can only maintain a person with mental health d/o.  Its all about picking answers that sometimes do not seem like the thing that a nurse would say.  I wish I would have had this one book for test taking before I even started nursing school.  If you can find it and get it really quick it is a real help.  Its called A Good Thinking Approach to the NCLEX and other Nursing Exams  Its by Susan G Poorman, Melissa L. Mastorovich, Karen L. Molcan  ISBN number 978-0-9640556-3-6  It is really a must for learning how to eliminate answers and has really helped me.  It has improved my pre NCLEX scores.  Also use Lippincott's Review for NCLEX it breaks questions down according to subject and doing NCLEX questions ahead and learning the rationale for why you are wrong and is a great test taking skill.  Any NCLEX book that gives you  a rationale for each answer is great.  It is never too early to use NCLEX books. Sometimes the first test in Mental Health is the worst because they start out with the DRY material and intro and then gets better.  Good Luck!!