A safe migration starts with inventory. Record the website files, database, scheduled tasks, DNS records, email services, SSL certificates and any integrations that depend on the current server.
What to consider
Copy and test the application before changing DNS. Lower DNS TTL values in advance when appropriate, then schedule the final data synchronization close to the cutover time.
After the DNS change, verify the website, forms, email routing, SSL, background jobs and logs. Keep the old environment available for a short period if possible in case you need to compare or recover missing data.