Check content database sizes (<100GB, load balance Site Coll.)
Run orphan repair tool (KB 923904: stsadm –o databaserepair).
Run DBCC CHECKDB on all databases and address any errors.
Defragment databases (KB 943345).
Verify no upgrade timer jobs exist (see Deployment Guide).
Backup farm just prior to upgrade
Rename upgrade log file on all servers (file is cumulative).
Disable anti-virus (KB 936867).
Stop the WWW service on all WFE.
To speed up upgrade or if content DBs are greater than 25GB, preparetomove and then disconnect databases (can use batch file).
Logged in as the Setup account, run appropriate packages. Cancel SharePoint Configuration Wizard each time.
Determine best first server to run upgrade (see Deployment Guide)
Run upgrade using “psconfig –cmd upgrade –inplace b2b” command line. Upgrade Process is fully described in KB 948780 (Baretail can be used to monitor upgrade log).
Verify upgrade was successful using the upgrade log. Check the version number in CA (see Deployment Guide).
Complete upgrade on all other servers as described in above order
If you detached databases, begin attaching again one by one, upgrade process will be done when they attach. There is a more advanced parallel upgrade process for very large farms available in deployment document.
Install WSS and SharePoint Language Pack updates for both WSS and SharePoint.
Enable anti-virus (KB 936867)
Start the WWW service on all WFE
Complete a full crawl of all SharePoint content [New features and change log lost with detach (KB 949603)]