Well, considering that I intended to paint a simpler, more intimate piece, when it came to cleaning up the sketch and colouring the various flat colour layers it turned out to be a surprisingly more complex scene than I'd first thought.
Anyway - all the individual layers of the painting are split up, so "all" I have to do is dive in and start painting, knowing that I'm not going to 'go outside the lines'.
In my previous IRL life projects I've attempted various methods of painting - from a loose sketch to just blocking out in grey, adding colour later and by trial-and-error and the many pieces I've painted since I started this project in April found this method of painting works best and most efficient for me:
Draw a sketch that's as tight/loose as I need it to be with various elements on different layers.
Group the line layers together based on how deep they're supposed to be in the scene.
Paint single colour 'base' layers that represent the silhouette of a character/item in the scene.
Paint additional flat single colour layers on top of those silhouettes for the various parts of the character/item.
Name every single layer so it's not a pain to figure out what layer is what.
Group layers in folders so it's easy to show/hide characters/items as necessary.
Lock the transparency on every single layer so I know I'll never "go out of the lines".
If I haven't already, fill my flat layers with the colours I'm going to use (as you can see from the image I've posted, I'm using any old random colour to help me identify the various colour layers)
And after all that prep work...
Load up my brushes and start painting.
And that's what I'm about to do...and, like eating the pizza crust first, I'm going to start on the background so I get to finish on the real fun stuff.