Good morning steemit, I've been working on some things I'd like to share with you.
Supplies: sketchbook/piece of paper preferably artist grade paper , hot pressed watercolor paper or design paper.
A slightly wide brush, Wide enough to coat your size paper easily.
(Black ink preferably liquid acrylic ink, but you can use sumi or Indians ink.
Crow quill or something to ink with (micron/brush pen so on, but if you want your lines to have this look u'll have to try a crow quill)
Apply acrylic paint in a soft and even manner, brushing in one direction (all horizontal/all vertical)
When deciding on a "complex" doodle design, the main things you need to keep in mind are,
form, texture, weight, and variation.
The form is the different main shapes than make up the drawings, in this case I chose fish scales, bones, and muscles/string, even a little wood. But choose your forms before hand and sketch them out.
Next you should think about the texture, which you want to keep representative and varied, so a bone should have scrapes and holes and cracks, the scales, should be overlayed, and so on.
You should also keep in mind the weight of your lines and which objects are in front of which.
I also vary as much as I can, vary vary vary, this gives a look of complexity.
Here's another small example using these techniques.