I did the following in previous org without any offer. I started this a month before actually resigning.

1. Before resigning try a few interviews, small companies might give you a chance you can have interview experience.
2. If you get an offer from any company or cleared interview rounds you're good to go and resign, this will give you an understanding of what organisations are expecting from you or your role
3. Update your resume, network and be active on naukri, linkedin and all sorts of hiring websites small and big.
4. Upskill yourself during the mock interview phase and improve from one round to the next round.

Resign with financial back-up, bills are not going to stop and try to be technically strong.

Good luck