Today I have been working on an illustrative drawing which twists and sometimes completely ignores the drawing principle of working big to small. 

I have a large set of Faber Castell marker pens and Gelly Roll gel pens that are not getting enough use. Well that has now changed as I am using them for a large picture inspired by Gustav Klimt. It’s actually a picture of his studio in a garden landscape. The thing with Klimt’s work is it has so much detail and when working with pens a different strategy is required from working with paint. 
There is no building up of layers or working from big shapes to small details. Instead I am working from foreground to background - small details first then colour in around them. Basically it’s the nature of the pens that has pushed me into making the decision to keep everything on one layer.

Notice that most of the pencil lines are very sketchy and serve merely to remind me of the approximate placement of things.
Here I have started working on the small tree by first of all firming up the pencil lines and then drawing in the leaves with pen.
Once the leaves are in I add the branches, these are drawn between the leaves giving the illusion of being behind them.
Finally I colour in the roof tiles between both the leaves and branches. If I reversed the process by laying in the roof colour first followed by branches then leaves, I would find it difficult to achieve a strong clean colour in the leaves. The majority of the pens I am using require the white of the paper behind them to show their purest colour.