When I talk about mathematics, physics and chemistry my best advice is you must go through NCERT books first. As NCERT books are written by a group of professors from reputed universities of India and everything is well explained as per your need. You can also read and download NCERT books online.
Now let's discuss helping books for class 11th and 12th. If you have chosen math then you must be preparing for CBSE/ICSE board as well as JEE. I am suggesting you with this point of view.
- For theory part - SL Arora or Pradeeps or Resnick Halliday (for advanced level)
- For Numerical part- HC Verma(best for basics) or DC Pandey or IE Irodov (for advanced level)
- Organic Chemistry: For theory Solomon's and Fryhle / Morrison- Boyd/ L.G.Wade and for numericals- MS chouhan
- Physical Chemistry: P Bahadur (for concepts) and RC Mukherjee(mainly numerical)
- Inorganic Chemistry: JD Lee and Vikash kumar Jaiswal for numericals
- RD Sharma or [SL Loney + Hall and Knight + Thomas Finney](for better preparation)
- You can also get math formulas.
ENGLISH Writing Skills:
- Prefer xam idea, oswal question banks and NCERT exercises.