Scalability: What you can do to lower your production hosting costs

What is the smallest viable production-ready environment that you can build?

What are the most common pitfalls that you can avoid when taking your site to production?

What changes need to happen to a site to lower it's scalability costs?

As an engineer working with customers, I've been wresting with these types of problems for the last several years. I'd like to share back with the community some of the lessons that we've learned.