Like others before I read loads of books, from official guilds to Kevin Mitnick’s books on social engineering and the Hacking Exposed books.
I then bought the Preplogic test exams and found them really poor. There were major mistakes on the questions and they were also very ambiguous.
After another recent post to this site I also got the Pass4Sure questions as well and found them to be much better. So I would definitely not bother with Preplogic again.