4
Maybe someone can add to this or fill in some detail, but this is what I did:
1) Leave everything on the original site until things have been working without problems on the new site for at least two weeks.
2) Back up the XOOPS database (structure and content) from the admin panel.
3) Make sure you have a list of of php and template files that you have hacked or modified. Either do a complete install of the latest XOOPS version at the new site or upload a backup of the old site from your own computer. I prefer a new, clean install. If you upload your site from your computer, you will need to edit your mainfile.php to reflect your new host's settings and you will have to make sure all permissions are correct. That is one reason I prefer a new install.
4) Restore your database using the admin panel.
5) Modules can either be installed fresh or uploaded from your computer if you have extensively modified them.
6) Fully test and bugfix before re-directing your domain to the new site.