The super star Joel Oleson's best practices regarding SharePoint 2007 to 2010 upgrade in a nutshell are:
- apply "K.I.S.S" ("Keep it simple stupid!") principle to your "upgrade plan". Come up with a road map and milestones. Don't roll everything up. Choose essential. Don't turn every service applications on. It's harder to turn them off. And it's actually resource consuming to have all of them running
- Create RACI (responsible, accountable, consulted, informed) chart to figure out the roles of the upgrade team
- Create a user group within a company to collaborate with them regarding an upgrade plan
- Learn what is in Out-of-the-box. "Don't play against SharePoint, but with it"
- Keep your hands off the content database. Don't interact with it. The upgrade will not get through if it notices the content database modification.
- Use testing\staging environment for test upgrade or even applying the service packs. Make sure that you introduce data from Prod to your testing environment. The exact configuration and content databases are highly recommended on the testing environment to run a valid test upgrade scenario.
- Consider a hybrid upgrade approach.
The Hybrid upgrade consists of the following steps:
1. create a "new prod" (with hardware capacity for SharePoint 2010) - the exact copy of the prod with exact configuration and content database 2007
2. test the functionality on the new prod.
3. set old 2007 farm read-only.
4. start in-place upgrade on the “new prod”
5. test the functionality
6. let the users start using the 2010.
7. drop the read-only 2007 server
- Do the homework : understand before use it. Read about SharePoint 2010 Upgrade first.