you don’t even have to find and turn off the breaker. Just turn it off at the switch before you mess with it.

One word of caution here. If the light fixture is hooked up to a three-way switch, it is possible for the light to be off and BOTH sides of the wire to be hot. This isn’t a common way to wire three-way switches and it isn’t to code anymore, but there are many homes out there with legacy switches wired as such. See: Carter 3-way switch.