Hi again and thanks for the comments.
I have many secrets

but they don\'t have anything to do with my drawings. Hmm, few tricks that I do use:

Zoom:
Zooming in when drawings helps acquire smoother lines. Especially nice when working with mouse. Must check the big picture once in a while, to be sure everything fits together.
Resize:
When the image is finished, shrinking it a bit can give a nice touch. Just like antialiasing in 3d games. Also makes the file size smaller for web uploads.
Layers:
Nice especially when colouring or dealing with transparency. I like to use multiply for colours and overlay for highlights and bumpmaps.
Eraser:
Drawing with computer, you can erase a million times and the paper never breaks.

Undo & Redo are in frequent use too. Sometimes I also use move, if a line is nice, but just in wrong place.
Last but not least:
Everybody to the Limit
*edits*
Here\'s how I imagined the the diaboli female:

1. Original
2. Added gaussian blur with radius 1 to smooth the lines a bit.
3. Added multiply layer and coloured.
4. Added overlay layer and touched up few spots.
Just my opinions. Thanks for reading.