Hey.

NEET is a very competitive exam and you'd be required to put in a lot of effort to crack it. But no time is too late to start. Nevertheless, You will get some benefit out of it.

Try to Frame a preparation plan for NEET by making  a complete time table of all the topics you need to cover in a particular time. Separate time for mock tests, solving past year papers etc. 

Make sure while attempting these papers you note the areas that you are lagging behind in and spend extra time on that. Also take the tests by setting a time limit so that you become efficient.

In case of any doubts approach your teachers / coaching classes.

Set separate time aside to revise whatever you have studied as it is very crucial.      

Make sure that you are using the right resources. Pay attention to NCERT textbooks along with any other material that you have.  

Best of luck