First, OpenCore is bound to not work at all. Just remember that.

There is a slim chance that OpenCore could corrupt your macOS installation, and you will have to go back to your previous version of macOS, which is not easy. This is why it is very important to make many Backups of your Mac.

Make a backup using Time Machine, not third party software. Time Machine is what we'll use if something bad happens to your Mac.

Also, make a bootable USB drive of your macOS (or OS X) version. So if something horrible happens, we can reinstall macOS easily, and start from the beginning.

2011 Macs and newer can reinstall macOS using Internet Recovery, so you do not need to make a bootable USB Drive. Although, if you feel more comfortable armed with one, you can never be too safe.

iFixit has a link to making these drives: Créer une clé USB bootable

Make sure you click "About This Mac" and find the version your Mac is running. This way you will know what version to download.