Define the scope of your data migration project
Identifying the project's scope is the first stage in every data migration process. This will enable you to assess the amount and type of data that has to be moved. Additionally, outlining the project's scope will enable you to establish a timeframe and reasonable expectations.

Clean up your data before migrating it
It's crucial to clean up your data before migrating it. This entails eliminating any duplicate data, fixing any mistakes, and making sure that all of the data is formatted correctly. In order to ensure that your data transfer is effective and that your data is useful after it has been migrated, cleaning up your data will help.

Choose the right tool for the job
The process of moving data around can be done with a variety of techniques. In order to ensure that the transfer is successful, it is crucial to select the appropriate technology for your unique project. When selecting a tool, you should take into account a number of criteria, such as:
How big is your data set?
How complicated is your data?
How your source data are formatted.
The structure of your intended data.

Map your source data to your target system
You must map your source data to your target system after selecting a tool for your data migration. To do this, a strategy for transferring each piece of source data to the intended system must be developed. It will be easier to make sure that all of your data is transported accurately and thoroughly if you map it out.

Extract your data from the source system
You must extract your data from the source system after you have mapped it out. Typically, an extraction tool offered by the source system's manufacturer can be used to accomplish this. You might have to export the data manually if there isn't an extraction tool available.

Transform your data into the correct format
You must convert your data into the proper format for the destination system after you have retrieved it from the source system. This could entail altering field names or lengths, converting file formats, or carrying out other modifications. Many of these activities can be automated with transformation tools, but some manual transformation may be necessary as well.

Load your transformed data into the target system
You must load your data into the target system after transformation. Typically, a loading tool offered by the target system's vendor can be used to accomplish this. If there isn't a loading tool available, you might have to manually input the data.

Check out the complete guide on Salesforce Data Migration
For more help connect with Salesforce CRM Consultant