I do not have a lot of tips for you, I am afraid, other than asking you to go through the basic textbook for each subject, make detailed case lists and solve as many mocks as you can. JRF also requires a luck factor. However, with regard to your PhD issue, I can tell you that several top NLUs, including NLSIU, NALSAR, NUJS and NLUD offer University Research Fellowships to some of their PhD students, which are monetarily equivalent to the JRF. Other NLUs may also offer those, I know for certain that these four do. Given that you have already cleared NET, you just need to come up with a robust proposal and clear their interviews. You will have to do occasional university work other than your own research, but it is not a bad deal overall. You may give it a try.