I always stumble upon excellent arts with effects I have no idea how to create. I bet most effects are very elementary and easy to create, but I just don't know how.
The most recent ones is this
How to create the "old" effect/stain? How about the fire glow+fire stain on paper?
What's the most excellent effects guides you've seen online with great application of effects to artwork?
You don't need to answer all of them, any would be appreciated.