If you are worried about it, you should probably involve professional services. But, in case you cant/wont make sure you have everything backed up in case it blows up and you have a suitable rollback. Test it in a lab, and test your rollback.
In fairness, a SP (even versions now days) are usually simple processes, but you never know your luck.
I agree with Marvin, There are 5 steps to upgrade
Run Deployment scanner for the new version
Test the upgrade in a LAB
Follow the upgrade instructions that come with EV
The process is simple but have a backup of everything and read the instructions carefully. If you are unsure then either use Professional Services or find a Symantec Partner to help you with the upgrade