Check the recording before you process it. The clipping guide explains how to spot distortion that cannot be undone, which decides whether you clean up the take or record it again.
If the recording is usable, remove background noise next, then set loudness to a consistent target using the LUFS guide so episodes and videos play back at similar volume. If you would rather not record narration at all, read the AI voiceover comparison for usage terms and limits before relying on a generated voice.