Analyze the website for Migration - Prepare list of extensions, plugins, modules, articles, media, etc. Compatibility check for latest version.
Backup the Joomla website to USJF staging server
Migrate the website - Template, Extensions, Articles, etc. Customize extensions if needed.
After completion of migration in staging server, test the website for bugs.
Request client feedback and approval for the migrated site.
Take the Live website backup. Move the migrated website from staging server to Live.