It's important to understand the layers palette. It can either be a big help or a big headache.
The Basics:
- You can only edit one layer at a time - the active (selected) layer.
- You can drag layers up and down the list.
- Remember – create a new layer for each step so you can go back and edit the layers individually.
- Delete layers: Drag-&-drop the layer to the trash can at the bottom.
- Create new layers: Click the double squares icon to the left of the trash bin. (or CTRL-SHIFT-N)
- Duplicate layers: Drag-&-drop the layer you'd like to duplicate on top of the double squares icon (or CTRL-J)
- Hide layers: deselect the eye icon to the left of the layer
Suggestions:
- Name your layers: If you're working on a complex project with several layers, it helps to name your layers for easy distinction ("lime circle" v. the default "Shape 1 copy 2")
- Grouping also helps when working on a complex project. For example, say those 3 circles above are part of a poster project with 50+ layers, you can condense the layer palette by selecting & grouping the associated layers into one group/file (CTRL+G)
so it looks like this (above), instead of this > |  |
