No Substitute to Self preparation - There is no substitute of CAT self study in exam preparation as it does not require any coaching until and unless you are stuck.
Take Mock Test - Before beginning your CAT preparation, the first step would be to take a mock test to judge where you actually stand.
Know the CAT Exam Pattern - Once done with analyzing what you need to know on how to prepare for CAT without coaching through a mock test, you need to check the exam pattern as well as the syllabus of CAT.
Time Management - Make time management your priority. It is not just preparing Verbal Ability or Reasoning or Quantitative Ability but preparing for all sections together with proper time management.
Create Study Groups - A good company can make or break the results. Hence, it is advisable that candidates must try to actively seek out people who are or have already appeared in CAT exams.
Get the Right Study Material - The market is flooded with ample CAT preparation study material. Those who are preparing without coaching must keep an eye on which are the best books.
Use the Technology - Just because you are not going to any coaching classes does not limit your access to the internet. Browser throughout and make use of Google services.
Be Motivated & Have Faith In Yourself - Although not directly, this factor is of utmost importance as it acts as a guiding force in any area. Make yourself motivated by adding a positive sticky note in front of your desk.