What's the next step? This book has laid the groundwork for a deeper understanding of JavaScript and computer programming. Now, you're ready to tackle 'real' problems, unencumbered by the basics.
If you are studying with Launch School, you will soon begin breaking down problems and developing solutions in JavaScript using object-oriented principles. The things we covered in this book are the things that must be automatic to an everyday JavaScript developer. If you have yet to reach that point, don't panic. We'll go through them again in JS120 or JS225, depending on which track you are enrolled in.
From here, Launch School students should continue to review and expand upon what they have learned by working through the lessons of the Object-Oriented Programming course. Also, don't forget to take advantage of the Exercises resource provided by Launch School! The collection of practice problems in the JS120 - Object-Oriented Programming in JavaScript section will provide an excellent way to continue practicing object-oriented programming concepts.