As you asking for get make good marks in cat exam, so for it I can say you need to know firstly its exam pattern /syllabus and do collect good books and do following things :

Take mock tests in online environment

Analysis is must

Focus on strength

Practice a lot

Set target but be open on number of attempts

Time management

Don’t compromise with accuracy

Reverse action

Relax well before your D-day

Be focused and keep calm during CAT

Good books for exam preparation :

How to Prepare for the CAT Common Admission Test (Set of 4 Books) by A
Rs 2,451.00

Complete course Pack for CAT [Set of 12 Books] (Quantitative Aptitude, Data Interpretation, Logical Reasoning, Verbal Ability)
Rs 3,200.00

Previous Years' Solved Cat Papers
Rs 382.00

Quantitative Aptitude for Competitive Examinations
Rs 360.00

Quantitative Aptitude for IBPS/SBI/RBI/SSC and All Other Exams
Rs 349.00