Well i must say, that’s great thought of you and just a perfect timing to start off with a hobby called SDL (self directed learning) if you were in 9th or 10th class. I know most of you may not satisfied or approved of this method but i can boldly say that it is a method to make you different from rest of those students who only mug up what had been taught in the class. Right now ,you might be thinking how is that possible?!!Read the topic that had been taught to you and dig into it more deeply(you can Google it,use kinder and other books as a source) and try to gain extra knowledge about it! If you are having problem with time and thinking that you wont be able to cover all the topics like this then do SDL in those topics you have interest!!
Well if you are10+ student then ,no worries !! Study consistently and thoroughly all the topics of phy,che & especially bio (dont dare to skip a single topics of biology!!) And during weekends go through the neet 10yrs solved paper accordingly the topics you have just covered in the entire weekday . Dont think too much about neet .The one thing you need to be serious about is that you have to work your butt off to score excellent marks in 12th board exam!!! That is same as preparation for neet! I wish you all the best for your future