I am going in for TSA pre-employment testing, help!!?

I wanted to see if any one could suggest ways to study for the pre-employment TSA screening test. I have taken this before and failed. I think it was because I was in a hurry, and i was also having trouble reading some of the Xray pictures that they show you. I was wondering if maybe there was a website that could help you learn to read a security xray better. Any other suggestions are appreciated as well!!!! Thanks