Here’s the right sequence to update SharePoint 2010 to service pack 1 and cumulative update.

1. SharePoint Foundation SP1
2. SharePoint Foundation Language Pack SP1 (if you have any other than english.)
3. SharePoint Server SP1
4. SharePoint Server Language Pack SP1 (Again, if you have any other than english.)
5. Reboot the server
6. Run the SharePoint Config Wizard (In my case I had to run it twice. The first one failed because of the User Profile Sync need to be started manually)
7. SharePoint Server Cumulative Update (starting from June 2011)
8. Reboot the Server
9. Run the SharePoint Config Wizard
10. IISReset
11. Start Central Admin and verify the Manage Services on Server to check that everything is started as before.
12. Reset the Search Index
13. Start a full crawl.

I know that some reports said that Server SP1 contains Foundation SP1, but by installing the Foundation SP1 before the Server SP1, it will overwrite any update push by the foundation SP1. And in this way, you will be sure to update everything that it needs too.

However, for Cumulative Update, Stefen Goßner mentions in his blog:

Be aware that the SharePoint Server 2010 CU contains the SharePoint Foundation CU. And the SharePoint Server 2010 with Project Server CU contains Project Server CU, SharePoint Server CU and SharePoint Foundation CU. That means only one package has to be installed for the SharePoint 2010 product family.

Full article is here. Stefan provide also links to download all required patches.

Also, take a look of the SharePoint Update section in Technet.

Tags: CU, Cumulative update, download, package, Service Pack, SharePoint 2010, SP1, step by step, Update