Many people know that machine learning techniques can facilitate learning from, and adapting to, noisy, real-world data, but aren't sure how to begin using them. Starting with two real-world examples, we will introduce you to some libraries that bring machine learning techniques to your Rails applications. We will then dive into the art of feature design, one of the first practical roadblocks that many people encounter when applying machine learning. Feature design is the challenging, subtle, and often trail-and-error process of selecting and transforming the data you provide for your learning algorithm, and it is often the hardest part of using these techniques. Our goal is for you to come out of this talk with the tools necessary to think about machine learning and how to apply it to your problems.