How to transfer your WordPress blog to a new server fast and safely
2) Prepare your blog in the old location
1. Export your database
* Enter the Plugins admin section of your old dashboard, deactivate and delete any plugin that you won’t need in the new home of your blog.
* Install Better Delete Revision plugin or any plugin that will clean your database, and delete all stored revisions of your posts, if you are sure you won’t need them.
* Install BackWPup, a plugin that backs up a blog’s database even regularly. It can also backup files (plugins etc), but we don’t need that. FTP allows better control of what and how is transferred, making a mistake less possible.
* Create a new backup job and in its settings select to backup only the database and a simple (txt) list of your plugins. Select the “Backup to Folder” option.
If you feel (and have reasons to be) confident, you can deselect (exclude from the backup) database tables of plugins that you won’t use in the new installation of your blog. Leaving them as they are won’t harm; better keep them, if you are not absolutely sure you know what to delete or not. In the same tab (DB Backup) put a checkmark in the Gzip option to have the sql (database) file compressed.
Go to the “Jobs” menu to run your new backup job. When the plugin finishes your backup (its a matter of seconds), click again on the “Jobs” menu to refresh the page and download the backup file to your PC. Extract its content in a clean folder.
You must see there at least an SQL file (compressed or not), that contains your database, and a txt file that contains the list of your plugins.