Notes:
0:34 What is a tile?
0:51 What is a tileset?
1:15 Tile atlas example from Super Mario Bros.
1:28 What is a tile atlas?
3:56 In general, you want to ensure the left and right sides of the tile correspond with each other
4:39 Start painting
5:35 Select a lighter shade, create a new layer, and add more detail
5:46 Add more layers of highlight as needed and use a lighter shade each time
6:05 Create additional layers for different parts of the tile
6:41 Paint shadows on separate layers
7:50 Duplicate the dirt layer
7:58 Add noise to the layer
8:03 Rasterize the image
8:09 Select Uniform (and Monochromatic if you want your noise to be only black and white)
8:24 Scale it up to make the noise look like a pattern rather than noise
8:33 Delete the vector mask