I have been in a bad form(not in a good frame of mind) recently. That's solely because of my inability to solve combinatorics problems. IIT-JEE is around the corner an I want to get to the level of IIT-JEE (around 250 points problems). I've read many books for IIT-JEE (combinatorics section especially) but still I feel there's some flaw in my understanding of concepts in combinatorics. I do not go to any coaching now as I feel self studying is more important at this time. That's why I'm asking you for help. I do not have deep interest in combinatorics as much I have in calculus. My inability to solve problems in combinatorics has lead to frustration and poor performance in other subjects. I don't want to ruin my IIT-JEE. Please help.
Please share good techniques (which can be generally used for problem solving), theories (which generally come in exams) and some sources.
Another problem is time factor. I don't have much time to read fat books, etc.
Any sort of help will be appreciated :)