My basic steps each time OC updates:
1) Make sure I have a backup of a working EFI folder from the current working release.
2) Copy the new OC files over the existing EFI directory
3) Manually open my existing config.plist and the example config.plist from the new OC version in propertree
4) Carefully go through, checking and comparing for new entries, or removed entries - takes about 10 minutes.
5) Having edited my config.plist as per step 4, check it for sanity at:
https://opencore.slowgeek.com/ (currently only at 0.66)
6) Reboot & cross fingers!