September step by step (Patreon)

I wasn't sure if I wanted a sepia-ish colour scheme or a pastel colour scheme. Decided to start with light browns, then layer other colours on top.

The above colours were done on two layers - one for the foreground, one for the background.
I put a new layer above the foreground layer, then clipped it to the layer below, then airbrushed some colours on top.

Added a new layer on top of everything else and just laid colours on top. Not really sure where the colours are going!

More laying colours on top on a new layer.

And more laying colours on top on a new layer!

I repeated this many many times, occasionally merging layers down so I could use the blend tool to blend the colours together.

After quite a few iterations, and using a levels correction layer to brighten the colours, I got this:

I coloured the lines a bit, added white highlighty bits absolutely everywhere, and then used a colour adjustment correction layer to make the colours more sepia-ish.

Done!