First of all don’t think that you are weak in these subjects. If you practice a bit , you would be great in all these subjects also . So some of the tips are:
STUDY NCERT: See if you ask me a single best book and must to know book I would definately recommend you to do NCERT. No book can compete with this. If you study NCERT properly you would definately score 120+ in each subject out of 180 .
REVISE: The thing which is necessary for boosting your confidence and retaining things for longer is revision . Revision is the key for success.
PRACTICE MCQS: Only studying would not help you. You have to know as to how to apply the concepts . For this practicing mcqs is must.
MANAGE TIME: You have to give proper time for each and every subject with proper time given in revision.