If you want to study online for free, you can do that with the help of ample study material on the Internet. You can also get youtube explained videos for free. What I would suggest is that try to get hold of some good coaching materials meanwhile. It will help structure your study plan and you will know exactly what to do and how to do.
If you want to go for coachings, these are some of the prestigious ones:

Global Academy

Elite IIT Institute

GATE-Indian Institute of Tutorials

CGS-Center for Government Services

Global Teachers Academy

iLearning

HelpBiotech Academy

Chembiosis Coaching Center

Academics

Career Plus

Gurukul Edutech

Elite Academy

Laureates Academy

HIRE UGC NET/SET Guidance Center

Amrita Global Education

Professor Academy