You need to fill JOSSA as carefully as you can. If you have got a great rank but still you messed up your choice filling, documents verification, chances are that the one who lagged behind you might get a better choice.
Firstly if you're not sure about your interest in a particular branch, you should go through the course structure of all the branches and see which subjects interest you.
You should also do take care of:-
How to check: Just google "
Another General Mistake- Don't tell your password to anyone. There are so many incidents of people complaining that their preferences have been shuffled. DONT TRUST ANYONE!
How to check: For batch size, search JoSAA Seat Matrix, For the latter, search "
How many choices can you fill in JoSAA?
The number of choices to be filled in JoSAAcounseling depends upon whether you did pass in JEE Advanced or not. Because, if you don't pass into JEE Advanced you'll have IIT's out of your options. IIT's take admission only through JEE Advanced.
In case you fail JEE Advanced you can fill around 300–350 choices and if you've passed JEE Advanced the number is more than it. So, don't hesitate to fill more options. But be careful while filling the options as once they are filled these options cannot be changed and if you've allotted one college the options filled below that college get removed automatically and you'll get a college filled above it or the same.
For example, you've filled IIT DELHI Electrical as option 10, IIT BOMBAY Electrical option 7, and IIT KHARAGPUR Electrical as option 11 and you've been allotted option 10 in the first round. Then in the next rounds, you cannot get options below 10. You can get allotted only between option 1 to 10. And rest of all the options are automatically removed.