Step 1: Check your Extensions
check the list of extension used and extensions which are not used anymore and data from the extension need to be migrated.
step 2. make your infrastructure for Magento ready
*prepare hardware requirement which fulfills magento2 store.
*install magento2 data migration tool
*make all the custom changes in data migration tool
Step 3: Initiate the migration steps
*check network access is available for the Data migration tool to connect to Magento 1 and Magento 2 databases.
*Identify the list of custom modules in the current version and check if customization has an impact on the core module, if yes those modules need to be integrated
*Stop cron jobs and activities in Magento 1.x admin panel.
*Migrate store settings and website.
*Perform manual copying of media files from Magento 1.x to 2.x store.
*Make use of the Data Migration Tool to bulk upload database from Magento 1 to 2.
*To migrate data gathered by extensions, you will have to download the Magento 2.x compatible version of the same extension.
*If there are differences in structure of the custom modules and extensions in the 1.x and 2.x versions, use the mapping files provided with the Data Migration Tool to set things right.
*Reindex all Magento 2.x indexers.
*There will be issues encountered at every step, those should be addressed till you get a clean version.
Step 4: Perform system integration testing
create an overall system integration testing to make application free from critical issues.
Step 6: Turn off Magento 1.x and turn on Magento 2.x store
its time to turn of the magento1 store and turn on magento2
*Turn the maintenance mode on for your Magento 1 store.
*Start Magento 2 cron job.
- Cache the pages in Magento 2 site using a caching tool of your own preference.
*And you are live now! Your new Magento 2.x store is ready for you and users.
If you think a technical expertise would do good, go for a Magento managed services to take care of the technicalities.