How to create white lines
Here's a quick, simple and effective way to produce thin white lines against a dark beackground. You can use this fo all sorts of things; fence posts, flying birds, washing lines, tufts of grass, branches on trees, and so on.
To reserve the white of the paper, just press into it quite strongly with your fingernail nto leave an imprint. If you haven't got any fingernails that are long enough (!) or you want to be slightly more accurate with your marks, then use a toothpick, key, or empty biro.
Then simply rub over these lines from side to side with a soft pencil held almost flat to the paper surface, and the white lines will magically appear!
Click on the picture to see a larger version.