JEE

You would get much more suggestions and ways to prepare for JEE all around the web. Since I have also been through this stage, I would just suggest you what are the don'ts during the preparation:
1. Ncert is the base. If you haven't get through each and every chapter thoroughly. Mark this day as your Day 1 and start preparation.
2. Test series should not be bunked no matter whatever condition takes places during that time. Don't ever miss any test. They may seem hard to you in the beginning and very exhaustive but that's the only real practice and hard work you're doing for the JEE.
3. Go for one book for each subject after Ncert. If you have joined any coaching go with their materials. Too much of books and material would just lead you to no where. You don't need to do any research in this field right? You just want to grab a seat in that prestigious college. You just need one seat not many !
4. Never waste your time on reading too much of theory if you hang up on any question. Sometimes it's not your lack of knowledge but lack of concentration at that very point. Move to other question and note that point somewhere which is handy and you can go through anytime you want.
5. Read. Solve.Read.Revise. : Don't mess with the sequence. You have to do this on a daily basis. Every single day you waste would harm you. If you really want to get in, you have to sacrifice no matter what
6. Last but not the least, No matter what level of student you're , You have to work hard for your seat yourself. No teacher, No book, No guide would hold your hand and help you in this process. Do it for yourself in your own way. Motivate yourself on your own on a daily basis and reward yourself too for every good thing you so towards the process.
Hope this helps!