If you know that your design is going to have multiple parts where they make up an assembly, the best way to begin is to create empty components from the very beginning and activating the one you want to work on. This way, all your sketches, features, and joints you use will all be organized within that specific component. Watch the video below as I walk through the thought process and demontrate why this is an important and useful best practice for designing in Fusion 360. 

Let me know if you have any questions, I’d be glad to help! 

Cheers,