it is usually advised to fill the choices as per the preference of colleges and departments, for example CSE in NIT Trichy ids priority followed by CSE in NIT warangal, you can fill CSE at NIT Trichy at serial number 1 and CSE at NIT Warangal at serial number 2 and so on and so forth.

but the previous cut off of colleges should be taken in consideration, it is better to research over the cut off of colleges then make a preference list of colleges and fill accordinly