Well let me first welcome you to the GMAT club! Everything you need to know, and find, is available on our website.
A 3.5 and 3.6 respectively is actually much better than you would think, especially for an engineer. It is right at or above average for all Top 10 schools. As far as the GMAT goes, you should definitely shoot for 700+ and preferably 720+. All top 10 schools have average GMATs of 710-730, so you should shoot to atleast be in this range or higher. Something higher will help your profile somewhat, but you just need to make sure to atleast get to that 700 mark.
You should really do some research around the forums, and your desired schools websites to get a feeling for what else a strong applicant brings. GPA, GMAT, and LoR are great to have, but as an applicant you must also bring leadership experience, extra curriculars, stellar essays, solid resume, and great work experience. Right now is a great time to start your journey b/c you can spend a good 3 months or so studying for the GMAT, and be right in time to put together some solid applications for Round 1 applications come next season. Round 1 is the best time to apply, with the best chances, and will give you opportunities to stagger your applications into R1 and R2 if needed.
Take a look at this post: the-bed-wetting-applicant-thread-for-116569.html?fl=menu
to see what average stats are at the schools you are considering applying. As far as a study plan, start here: gmat-study-plan-start-your-gmat-journey-80727.html?fl=menu
I would also consider ordering this book: http://www.amazon.com/Complete-Start-Fi ... 1935707000
This will really get you in the right mindset to get into a top 10 school.
Good luck and let us know if you have any questions we can help you out with!
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