There are 4 ways I Draw. that I know of...
1. I see an image in my mind and do my very best to try and get it out.
2. I have no Image visible,
but feel the need to draw/paint, and then I just try to be the best outlet I can be for the Image to present itself...
3. I use a external visual stimulus as a starting point, and then break away from it to let the image develop past its source.
4. Any combination of the above.