Start here:

So you want to learn Physics– awesome post by Susan J. Fowler
How to become a Theoretical Physicist-awesome blog by Gerard ‘t Hooft

Other Useful Links:

  1. NCERT textbooks
  2. Openstax– Free yet high quality textbooks(college/AP level and beyond)
  3. sparknotes study guides
  4. Hyperphysics
  5. Wolfram Alpha
  6. AP Physics
  7. Feynman Lectures
  8. How to be a Theoretical Physicist (advice and resources)
  9. Edx.org (online courses)
  10. Coursera.org (online courses)
  11. Better Explained (to learn math intuitively)
  12. The Physics Classroom
  13. Particle Adventure (have their own app, excellent for elementary particle physics)
  14. Physclips(demos and notes, by UNSW)
  15. Problems and solutions in dynamics (taken from Hibbeler)
  16. Feynman-Hughes lectures
  17. Sky and Telescope for Astronomy (look out for their newsletter. It is very informative)
  18. Encyclopedia of Astronomy and Astrophysics

Blogs/podcasts on Astronomy/Astrophysics

  1. Bad Astronomy by Phil Plait
  2. Startalk Radio by Neil deGrasse Tyson

For a list of useful Youtube channels, click here

More links will be added periodically, keep checking for updates)