Layers are pretty easy to work with and they allow you to experiment while sketching. They stack elements over one another so you don’t have to modify parts of your drawing that are ready when editing those that are not yet finished.
Add as many layers as you need, and control them by turning layers on and off, deleting or merging them. The video below offers a quick explanation of all the possibilities layers offer, including copying a layer from one project to another.
Good sketches!