Hi Subhash,
Try to study all the topics with concentration and make sure that you can attempt any type of question related to the topic that you have studied and i m giving u some scoring n easy topics so dat u can plan accordingly......
usually topics of 12th class is relatively easier compratively to topics of 11th...... In 12th topics , i wud suggest u dat modern physics is d most easiest topic in iit jee and u can score very high as its weightage is also good so if u can score in this topic den u r always better placed ,,,,,after this i wud suggest dat waves and simple harmonic motion r some easy topics from class 11, again for 12th ,magnetism & current r scoring topics........
All the Best !!