How do I pass this aptitude test?

Good evening all,
Please I need everyone's contribution. I wrote a Diamond bank test sometime ago but was informed that I was not successful. I will be writing one soon.Please can those who were successful give me some tips on how I can make it because I cant afford to blow this opportunity again. What could I be doing wrong? Which G-mat book should I use? And does anyone know where I can enroll for local G-mat class?
Suggestions please.My email is [email protected]. God bless you all.