Android is the most popular operating system in the world and growing rapidly. Emerging markets are important, but not the only reason to write the most performant app possible. Building solutions that serve all of your customers will become increasingly more important. I will share what I've learned over the last year while writing apps to install solar systems in rural Tanzania. You will learn strategies for shaping your architecture, how to make your app work well offline, how to keep your APKs trim, and how to set up your test labs and conditions.