As I'm working up my plot for a project, I'll draw mind-maps or a spider drawings taking my inspiration from the three-act structure or Save the Cat! beat sheet to create a rough map of my story. Here's an example, a mind map I doodled for my hi-lo middle school novel Iggy's World.

It's a great way to brainstorm on structure and I'll do this sort of mind-mapping several times as I develop a project. If you haven't tried it yet, I highly recommend giving it a go. Here's the thing, though: what we're doing in this exercise is only a brainstorming tool. Don't get stuck on the idea that this exercise is what your project will look like in the end. I do one of these sketches of my project almost daily and it changes almost daily, as new ideas crop up in the writing. So don't feel that the ideas you come up with here are written in stone, or have to be "perfect." Instead, know that this is just a rough sketch of structure, and things will change as the project progresses. Have fun with it. Play!
 
As you likely noticed as you look at various story structures, especially the Save the Cat! beat sheet, we can start by breaking our narrative down into three simple sections: beginning, middle, end, or Act I, Act II, Act III.
 
We can break the story down further by dividing the project into two at midpoint. As you can see from my doodle above, I’ve simplified things and mapped out six main plot points. If you use the Save the Cat beat sheet, you’ll see more beats that you may find useful.
 
But many projects don't fit neatly into three acts. Check out this link, Beyond Three Acts: Different Structures for Storytelling.