During our times we used to solve a book. It used to be the toughest book in mathematics. It was a nightmare for us and for most of my classmates. My school never recommended it. But my father used to force me do the book.
When I came to class XI I realised how ahead I was with respect to my peers in terms of mathematical skills.
The book's name is legendary-"KC Nag".
I would suggest everyone to follow the book and go to tutors who follows the same book. Teachers often dislike this book because it makes them work hard. But hard work pays. BElieve me do this book for 3 months and we will see hell lot of difference in our mathamagical skills.