started with a little sketch of the outlines (in sketchbook)
tried various ideas to see what would look effective
here the tree is like a negative; in the second one the lines are not in wax, though they do resist in a different way as they are waterproof.
again the clouds are not strictly lines, they did look like lines originally but the wash did away with that notion. The white crayon is both whiter but less waterproof than the candle. Because it is white and can be seen more easily I applied less pressure and so it appears more transparent.
the black crayon I purposefully left grainy as I wanted to see if the wash would still take. It does, though the degree to which it does depends on a number of factors including the paint colour, quality etc.