Get a good Nclex-PN book, one for LPN's/LVN's. Look for one that is divided up into sections, med surg, pediatrics, ect ect. Saunders is always a favorite on this board. When you start a class, lets say pediatrics, go to that section, read through the front part and then start doing the questions. You would be surprised to found out how many teachers take test questions straight from NCLEX books
. If you don't want to purchase an NCLEX book yet, go to your school library and check one out. It doesn't matter how old they are, some things never change. Just make sure and get a new one to use before you take the NCLEX.
Also, look into the cd that comes with your classroom books. Many times there are questions either on there or on a website that comes with the books. Or get the workbooks if that class has any as an option.
Another source is to do a web search on what you are studying. You might find some colleges have questions online, or maybe a nursing site has an article on the subject with questions afterwards.
But ultimately the Nclex book is the best, you will be surprised how quickly you will start being able to answer them correctly.