Once you take your diagnostic test, its
time for you start practicing the questions from the GMAT Official Guide. But
the way you practice also has a lot to do with what score you get on your
diagnostic test.
Lets assume you got between 440 and 520 on
your diagnostic test from mba.com, then you need to sign up for GMAT classes.
However, if you score between 520 and 610,
then you probably will do fine with a few online GMAT classes and then you can
start practicing right away.
And if you score anything above 610 on your
diagnostic test then I suggest you sign up for GMAT classes anyway because with
proper training you will probably score above 720 on your main GMAT exam.