As I was doing another Service Manager 2012 R2 Upgrade lately, I added some minor improvements to my Upgrade to Service Manager 2012 R2 Checklist.
If you have any corrections or thoughts about improving the checklist, please let me know. I would be happy to update the OneNote file so others can benefit from your knowledge.
I provide this checklist as-is and cannot guarantee the accuracy or timeliness of information available from the checklist. In addition to this checklist, also check out detailed instructions by Microsoft on how to upgrade your environment to System Center Service Manager 2012 R2.