Detailed Review Of Preparation

Preparation for any of the Certification or Exams start with the First Day of the Class. Experience with the projects and Designing solutions helps you a lot to correlate business scenarios and Salesforce Capabilities. I can recommend below approach to prepare for the certification :

• Whenever you are designing Solution, Always look Data aspect of the requirement. 
  • Field Creation - Data type,usage,Indexing.
  • Page Load.
  • Sharing Calculations
  • SOQL Queries.
  • Object Schema - Internal or External
  • Trigger Designing
  • Archival Process for Obsolete Data
  • Clean Data. MDM
  • Skinny Table, PK chunking, Defer Sharing.
• On top of it, One should complete Salesforce Trailmix - https://trailhead.salesforce.com/en/users/strailhead/trailmixes/architect-data-architecture-and-management.
• After Completing Above course try some online tests.

Thanks,

Abhishek