Hi,

While filling the choices the branches which have the cutoff rank near about your rank increases probability of your chances of admission.

The seats are allocated according The the choices filled by candidate. So if you filled a college in first choice and if the seat is available at the marks you obtained you will be allocated.

If your marks are near about the cutoff marks of  branches of very high cutoff you should fill it in first preference.if your chances of admission are low you can fill branch of very high cutoff very down in your preference.

To know your admission chances in different colleges through jossa counselling and better choice filling you can use jee main college predictor tool. https://engineering.careers360.com/jee-main-college-predictor?icn=QnA&ici=qna_answer

Hope it helps.