can I prepare for jee main& advance by self study I am study in 11 standard

Hello dear aspirant,

Yes, definitely you can prepare for both these examinations by yourself. What you need is proper routine study of at least 6 hours a day. You can study in a slot of 45 minutes and can take break between two slots. You should also keep swapping between the subjects as studying for a subject for too long can bore you easily.
Use books by Amit M Aggarwal of Arihant Publication of your preparation in mathematics.
In physics you can consider books like h.c.verma and D.C.Pandey's books of Arihant Publication.
In chemistry study ncert books along with books by N.Awasthi and M.S.Chauhan of Balaji Publication.
These books will be quite useful for your studies.
Check your preparation time to time by solving sample papers of both the examinations.

Hope this helps