Hi Madhu,
Following are the things to consider for migration:
1) Sequence of data load : Prepare the lookup or reference data and load them before the actual data. Then follow the dependency chain and load the dependency data in a reverse order. So Account and Contact would be loaded last for example and country and
state data first as an example.
2) Prepare duplicate detection rules : Define the duplicate detection rules before migration.
3) Prepare Data Map : Prepare the data maps for CRM entities.
4) Test data loads with less data in test systems.
Few more useful tips below:
http://www.powerobjects.com/blog/2013/05/08/11-dynamics-crm-data-migration-tips/
Hope this helps.
-----------------------------------------------------------------------
Minal Dahiya
blog : http://minaldahiya.blogspot.com.au/
If this post answers your question, please click "Mark As Answer" on the post and "Vote as Helpful"