Oh boy... the GMAT... I took them 1994 -- so I'm sure things have changed.
I usually look at how a person did on other administered exams to give advice. What kind of prep work did you do for your SAT or other similar exams?
For some the practice books work great, for others they have seminars, and today, I'm sure they have online classes and exams...
The LSAT is a totally different animal -- you have to train yourself to think (and reading comprehension wise) totally different.