What steps do you take during the editing process to ensure a polished final product?

After the raw recording is finalized, I'll always go through it in my audio editor to look at the waveform for any breaths or mouth noises and remove them.

After cutting is done, I'll do some mixing to remove unwanted tones from the audio (like an echoey midrange hum that comes through when saying certain words).

Once mixing is complete, I'll apply a light compression so that all the audio is at the same volume level. This makes it easier for the listener to not only hear every word better, but not have to struggle with constantly raising and lowering the volume (most audiobook listeners are doing something else at the same time, they don't have time to worry about constantly changing the audio volume.)

Once everything is set, I'll remove long pauses so that everything flows smoothly, and one final pass to be sure I didn't leave any extra audio artifacts in the final mix. Then it's ready to go!