First off, I would like you to know a few facts about myself in order to get a context of things.It wouldn't be appropriate if we are trying to understand something with completely different backgrounds.1. I went for FIITJEE for 2 years.I loved Math and physics.I focused on math mostly because I liked it.I was good at math in my class.I was good at IIT related math.
2. I didn't qualify for CMI 2012 because by the time i had known about it, it was pretty late.And IIT preparation merely helps it.
3. Math at 11th/12th that is taught at school is NOT Olympiad math.It is applied mathematics. Having fun with Olympiad math gives you an edge at CMI examination.
4. I did not take coaching classes for Olympiad math.An IIT student spent some effort with me for not more than 24 hours in total.But that was sufficient.
5. I was doing math from various books and also checking out AoPS for new problems.
6. I used on spend on an average of 3 hours on Olympiad Math.Sometimes upto 8 hours depending on your interest.I don't want to use the work hard work here.It's more of your interest that gets you anywhere.
7. I did not know the ABC of Olympiad Math during 2012.But now I will be joining CMI in 2013 with a decently good background in it. Which means, all you need is interest for math.

About the CMI Exam

The exam pattern is highly variable.If you look at their past question papers, you will notice that they constantly change their pattern and the difficulty of questions.It is done so to filter out the drilling methods that go on in IIT.All the questions can be answered with the basics.I would probably put them on the level of INMO based on the time,number of problems and difficulty of the 2013 paper. A good balance between speed and critical thinking is important.

My preparation

Like I already mentioned.I would study as less than half hour a day or upto 8 hours a day depending on my interest.Therefore, spending quality time with the subject is important.Also, I did not prefer buying all the books I wished to have.I often used to download the free ebooks and find good problems and do them.A smartphone comes in handy :P

In mid 2012 I was checking on how to prepare for Olympiads and stuff.And i found a few VERY useful articles that will help any math enthusiast - Vipul Naik

I referred to the books that were prescribed on the site along with a few better books.I will be attaching the eBooks which I USED in a few days.That is, the ones in which i highlighted a few and stuff.They might have marking here and there with red color.It was used for marking the ones I solved :P If you want to find the fresh copy of any ebook just use Google wisely "'blah blah blah' by 'author' pdf ebook download.

I have shared my collection of math material that I collected and used on my Google Drive. https://drive.google.com/folderview?id=0B0z4bz7rv29yZVdHX2ZqRHh0Njg&usp=sharing . Most of the books mentioned below have been linked and a lot more. And the CMI Entrance Exam papers have also been linked up.

1. Problem Solving Strategies - Arthur Engel
2. Putnam and Beyond - Titu Andreescu
3. Try the books on Number Theory,Alegbra etc etc by Titu Andreescu
4. Problems from AoPS
5. A path to Combinatorics for undergraduates - Titu Andreescu
6. Functional Equations: A problem solving approach - B.J.Venkatachala
7. Number Theory by Burton
8. Geometry i referred only from 10th standard mathematics.If you want good geometry books you can ask people at AoPS.

Some questions in these books are very tough and it is up to you to wisely select a few do able problem at start then move on the tough ones.I didn't follow any pattern of the above books.I did a bit of the easy books that CMI officially prescribed and then moved on to randomly selecting a few good problem here and there.Gradually, increasing the difficulty of the problems of the chapters i liked.But in the end I made sure i finished the important parts which i liked from the above books.

I kept in my mind how a few questions of topics which i didn't like in CMI question paper.In that way, i made sure i didn't leave those parts off completely.Even though i wouldn't recommend anyone doing this. Like i mentioned above, CMI papers are highly unpredictable.Luckily for me the geometry was easy this time :P

THE Most important thing

DO NOT take learning as math as a job for the sake of examination.If you do so i can guarantee you that you will not happy even if you get into your desired college because competition would be the only thing that you would like. Therefore, the primary thing is to enjoy the subject! Read up a few journals online, read about the International Olympiads, People and their performances,check out the latest developments in the field of mathematics and stuff like that. Keep learning and have fun! :D After all it's just an exam.I realized that only this year when i was least bothered about how i would perform in my exam (That doesn't mean i was sleeping in the exam hall :D)

I will soon be posting on various opportunities Indian Students have in the field of mathematics,physics and other sciences.So check that out too!!

UPDATE: 11-11-2013  Sorry, I havn't been updating the content due to Procrastination.
UPDATE: 14-11-2015  Drive link updated. Sorry guys, Couldn't reply to any of your mails/ comments. Been busy myself.
UPDATE: 7-7-2016  Sorry guys, I don't maintain this blog much. I have gone through some comments and emails. Though, I would like to answer some math questions. It is really painful for me to see these challenging questions.

can a student from north india crack this exam.?

First off, I can't give you life advice. "I'm 20 years old .. I'm not sure whether I should chose IAS over this" .. etc etc... I'm not a counselor, man (come on!) .... Send CMI ADDMISSIONS the mail about your age concerns . I've written this post for math aspirants who live and breathe math and consider math as a profession. If you're head is in the game and you want to know more details, send the CMI ADDMISSIONS a mail. THEY REPLY WITHIN A DAY. USE THAT EMAIL!

For other questions, like some wise soul in the comments, use this website called https://www.quora.com/topic/Chennai-Mathematical-Institute which does precisely that.

As far as the math doubts are concerned. I've answered some questions within my reach. I've written all my books and references. Take it as an advice to shed some light along your path. Not a bible. Individuality is the key for human survival.

Please don't ask questions which are just rephrased from what I've answered.

I am preparing for jee.does the mathematics I am studying would help me for cmi exam ,if not should i only concentrate on cmi syllabus .how should I do it ..bcoz I have 1 yr left so please tell me sth abt it..

I really doubt you even gave it a proper read. Specifically for questions like these, I explained the position I was in so that you can gauge your position yourself and read the post. You don't have to copy paste it in the comments dude :P

For , Questions like "What do you think about Blah Blah book by Blah. Is that a good book?". Frankly speaking, I do not know. I study physics at a graduate level and I lost track of the current olympiad material. You should understand that this was me 4 years back. Ask people on https://artofproblemsolving.com/community/c260_india who are more informed :)

And please be sensible, I DO NOT work in CMI office. I wouldn't know if there are 10 students selected or a 10,000 students selected or what the cut off scores are or the number of letters in the 4th word of the 5th Question in the 2016 paper. They have their own website for that FYI.

Finally, I'm really glad from the bottom of my heart who make it into CMI or any other college of their choice to pursue sciences with this info and  in general how this post motivated you towards math. It really means a lot. Thank you and Goodluck :)