See the competition in JEE Mains is very high. It depends upon you if you want to join any coaching classes or not. If you join coaching classes then you would be able to clarify all your doubts whereas if you do not join any coaching classes then you would have to clear your doubts on your own. 

Since you are in 11th Standard you must start preparing from now itself . Read NCERT textbooks everyday. Solve exercise given in NCERT textbooks. Give equal attention to very subject. 

You also have two years for JEE so make use of it wisely. If you want to join coaching or not? Well it depends upon you. If you join coaching then yes you would also get notes of all subjects in detail. So think about it. 

If you still have any queries feel free to ask in the comment section down below.