Recently I tried getting into GSoC and I failed. These are the valuable things I learned that I would like to share so that you do not make the mistakes that I did. I am going to keep the following points short and simple.
This is the most important point in this list, I would suggest all you aspirants to start going through the previous year’s organization list as early as October-November, and get in touch with these organizations through their IRC (Slack, Gitter, etc.) channels. Interact with them and contribute to their open-source.
CHOOSE THREE PROJECT IDEAS FROM DIFFERENT ORGANIZATIONS.
I would suggest you look at three different organizations as this maximizes your chances of getting selected if you make proposals in three different organizations, as sometimes mentors would be busy and cannot get back to you in time, and this would affect you adversely if you intend to do multiple projects from the same organizations. If you were anyone like me, you might get nervous looking at the plethora of organizations and the project ideas and get overwhelmed. My advice is to stick to concepts that you are familiar with and love.
MAKE THREE STUNNING PROPOSALS.
Some organizations want stunning proposals and some organizations do not mind mediocre ones, but always strive to prepare absolutely stunning proposals. Google around and find reference proposals, explain what you are doing exactly, and give a clear timeline for your work.
SUBMIT YOUR DRAFTS EARLY.
Submitting your drafts will give your mentors time to go through your proposals as they will have many more proposals from other aspirants, this will give you some time to work with as they will get back to you with changes (if any) to be made to your proposal.
DON’T GIVE UP.
It might seem daunting when you not only have to work on one stunning proposal but three, at a time. If you can power through this and finish it, you will have no regrets.
There are other guides on how to get into GSoC which I referred to while trying to get selected myself, but they were not helpful to me, and with the experience that I have learned, those are my tips.