Preparing for my first interview in 12 months after 9 years as a customer-service rep

It has been 12 months since my last interview and I feel rusty. It has been weighing on me all week. I want to come across as confident and honest. How do you prepare answers?

Thanks for writing this out. I went through something close to it 12 months ago, and it settled down once I kept a simple log of every call and form.