Re: GMAT
^ I found a very nice teacher for quants. He gave me a lot of tips, hints, shor-cuts which I could not find from Books. I didn't get help from anyone for the verbal section.
One tip: If a question during the exam seems easy, it is NOT. There would be a trick in it. If a question seems very difficult/time consuming, it is NOT. There would definitely be a trick/short cut to do it.
Good luck!