Hello, 

        You need to study NCERT books thoroughly. And practice as many as MCQs with a particular time limit. Practice previous year question papers thoroughly in the time limit. You can get a lot of similar questions in the real time paper. 

 In chemistry , physical chemistry is scoring.  Keep your concepts clear. Read the NCERT well for inorganic chemistry.  Make mnemonics if necesaary. Read the periodic table well. Allot extra time for organic chemistry if it's weak.

In physics,keep ur concepts clear. Practice as many questions as possible.  Modern physics is scoring. Make the mechanics question simpler by drawing diagrams. 

Mark the important chapters according to the weightage given in the previous year question papers.. focus more on them.

U can get hand of any good question paper book.... Buy the solved previous question paper book. 

I would suggest you to go through well with NCERT books as it will help you to clear your concepts. Here are some important chapters of Physics & Chemistry you can prefer given below:

Physics

Capacitance

Current Electricity

Calorimetry & Thermal Expansion

KTG & Thermodynamics

Rigid Body Dynamics

Work, Power & Energy

Modern Physics

 

Chemistry

Chemical Bonding

Coordination compounds

General organic chemistry-II
 

Good Luck!