How to Organize a Large Project

I’m noobie to music production and I need some pointers on how to organize a project. I have Elements 10.5 and will probably be moving into Artist if there’s a sale soon.

My project is large and is closer to a film score than a EDM song. I have a few sections and want to add any number of improvisations to it. I’ll probably be working on pieces, sections, and will be experimenting quite a bit. However, when I approach it, I’m not ready to start at the beginning and work through. Are there any suggestions on how to organize this? Would I keep all parts for Section 1 in one place, etc. and then when I have all the components worked out, do a massive cut/paste into a new file?

How do you organize large projects and keep things accessible?