MBA especially CAT preparation should be of the highest standard. You will need to persevere to prepare.
Decide that you will have to do it.
Set a timer table and stick to it.
Plan your modus operandi atleast an year in advance.
Collect practice tests and schedule them.
Take guidance from a coaching centre or someone who has experienced it before.
Since its a long and arduous task your motivation level throughout has to be high.
Insure yourself by taking other tests like MAT too.
Prepare individually as well as in groups. Both have their own advantages.
Practice regularly and rigorously tests, tests and tests.
Identify your weak areas and instead of ignoring them , work on them. we tend to ignore the weaknesses. Also strengthen your strong areas.
Manage your time. this is the key.Keep time for activities apart from study that will keep your mind fresh.
Periodically create exam environment, invite your friends time your tests and get them corrected. You will know where you stand.
Keep your mind cool even during preparation.
Believe you can do it.