We’re still on hold currently but here’s an impromptu look at layers. It’s 20 mins long and it goes into intermediate level information but it builds up gently.
It’s come about thanks to a question on the Cartographer Guild’s web site on what different layer techniques would help in creating non-destructable maps (meaning that all the individual elements that create the world/continent/locality remain editable throughout the process).
It goes over the following topics -
Layer Styles
Layer Masks
Clipping Layers
Layer Groups
Smart Objects
Unfortunately, as this wasn’t scripted I realise I’ve missed out one of the biggest feature of Smart Objects and that’s the fact it can have non-destructive adjustments on it like Filters. You can edit the settings of an applied filter whenever you want by double clicking the filter in the layers panel in contrast to adding a filter to a normal layer and you only have Undo to save you. Multiple filters can be applied and subsequently edited at a later date with ease. Any sizing or rotating you do to the Smart Layer doesn’t effect the final quality as it would do if you’d reduced a normal layer in size, accepted it and then tried to enlarge it again.
Suffice it to say that there’ll be more detailed info in later tutorials specific to all the topics covered here.
Download versions
For easier downloading there’s a few different versions available (besides watching it directly in the browser here).
Right Click to ‘Save Target As…‘ in order to download them.
Enjoy. 
Adobe Illustrator has more features than its competitors .