IIT

Just do some simple things:
1.Go to your class daily.
2.Study 6-7Hour daily
3.Leave Social Networking Sites.
4.Contact with good students
5.Practice mathematics daily
6. regularly revises your organic and inorganic chemistry part.
Rest are same.
All the best.

To get an accurate answer, you should mention your category. If you are a boy in general category, then you might not get any good government college. If you are a girl, then you would get a good state government college like, College Of Technology, Patnagar.

Class 11th score doesn't matter at all. All that matters is 12th percentage. You will have to score more than 75% for eligibility. So, don't worry about 11th score. Study well to score as much as possible in 12th and in JEE exam.
Good luck.

Mechanical engineering is basically the engineering related to machines, their working principal, mechanisms, about the different materials used and other designing parts of various machines.

Hello Abhishek,
The best IIT for aeronautical engineering is IIT-Bombay. It has a great reputation. Its placement record is also very good. I feel you should seek admission there.

There is no such better college among the choices you gave. But, I would like to bring this to your knowledge that ISI is only for maths, whereas IIT is for engineering.

It is quite tough to get IITs. Please check your rank in JEE Advanced exam with the help of the link given below:
https://www.shiksha.com/b-tech/resources/jee-advanced-rank-predictor
Then check the college closing rank by this link:
http://josaa.nic.in/Result2016/result/OpeningClosingRank.aspx

Hello Ayaan,
Other than IITs, the highest salary packages were offered at BITS-Pilani. It was around 1.4 crores per annum. It was at the Goa campus of BITS-Pilani. It is a highly reputed institution in India and the best among all private universities in India. The fee is quite huge but you can have an education and placements equal to IITs.

According to the mentioned college name by you, DIT-Dehradun is a good option for engineering in terms of placement, faculty, infrastructure and laboratory, but it may depend on the branch, please confirm before admission.