It's completely down to you. If you have plenty of money I've met candidates who did a course for a week (Veritas) and sat the test scoring 790+. I sat the test by paying for Manhattan GMAT revision material and practice papers (by far the best i used, steer clear of Kaplan). I'd recommend doing it before third year, over this summer as it's much easier to prepare and focus on.
As im sure you are aware the test changes this August i think, with only writing 1 essay and not two. I found the essays particularly easy using a veritas model.
In terms of revision this is what I did:
I sat a full practice test and saw my score (it wasn't good like 590) without revision.
I looked back at where I failed, and then tried to focus on those subjects. The good thing about Manhattan GMAT (Kaplan didnt offer this) was that you could order your wrong answers in terms of topics and they have specific chapters covering those topics.
I did similar for the verbal section.
I think realistically it comes down to just continual practice and getting used to the problems, especially the ones where they give you two statements to answer the question, can be difficult to get your head around.
One final tip would be, the weighting of the GMAT favours verbal over maths. The higher the verbal in general the better your score. People seem to think if they 51+ the maths regardless of their verbal they'll do fine, but its better to 51+ the verbal.
Last edited by Jakeh; 17-06-2012 at 18:41.
edit: link from the page explains the mystery of "why the hell did I do a writing section?" :P
Last edited by Teenage Pirate; 17-06-2012 at 19:00.