Hi Soujanya,
I echo the sentiments and advice expressed here.
As a past mentor and also a student who participated in GSOC, I would say the most important part is to interact consistently and as much as possible with the open-source community of your desired project; before even proposal work has started. Especially, it would be beneficial to get to know your mentor; select a mentor wisely who has had experience in prior GSOC(s) or was a long-standing active member of the project. Once you prepare the skeleton of the proposal discuss rigorously with your mentor any avenues to enhance your proposal such that you will have a better chance of getting it accepted (this could be in terms of the general timeline and action items of the tasks, design details, and also any contingencies if you had more time at hand or lack of). Good luck!
Best,
Udayanga