HI Ravi,
The best way is to follow an official SAP course for this. You can get valuable information from SAP directly. Also you can check the SAP certification forum for best guidance SAP Certification
Don't forget that the diary PI experience has not be that SAP recommends and you can fail questions for this. Follow only SAP certification course and you have to be very careful when you read internet information, even the SAP.help one.
Regards.