Tell me about your editing and proofreading process.
You need to show the interviewer that you're a professional who's in control of the editing process. Lay out your procedure in a sequential, step-by-step manner. Give brief explanations at the end of each step to justify why you are doing it (ask yourself, What does this step achieve? What do I get out of it?). Assure the interviewer that you're diligent and thorough.
"I'm very diligent and thorough when it comes to grammar, spelling, and punctuation"”it looks really bad for us if a casual reader catches something that we didn't. A spell-check can usually catch most of the errors, but I always keep these things in mind when I'm doing a read-through of a piece anyway. On the first pass, I'll [...], because I'll be able to understand the writer's intent and I'll be able to give better feedback that way. Then, I [...]."